AWUS01 KWNH 311818
FFGMPD
MSZ000-LAZ000-TXZ000-010015-

Mesoscale Precipitation Discussion 1109
NWS Weather Prediction Center College Park MD
218 PM EDT Thu Oct 31 2024

Areas affected...Central & Southern LA...Southeast TX...Ext
Southwest MS...

Concerning...Heavy rainfall...Flash flooding possible

Valid 311820Z - 010015Z

SUMMARY...Potential for a widely scattered incident or two of
flash flooding is possible through late afternoon into early
evening hours.

DISCUSSION...A potent autumn cyclone and associated cold front are
pressing across the central portion of the U.S, while a strong
ridge remains entrenched over the Southeast. As such, a solid
core of return moisture across the central Gulf with total
Precipitable water over 2.25" is lifting north across Louisiana
and starting to interact/consolidate within the warm sector ahead
of the approaching cold front. However, stronger mid to upper
level jet remains well enough north that front is starting stretch
and flatten from east to west under these low to mid-level
shearing forces. Moderately clear skies throughout the morning
into peak heating across the warm sector has brought temps into
the mid-80s over low to mid-70s Tds, resulting in a moderately
unstable environment across SE TX into much of central and
southern LA with MLCAPEs reaching 1500 J/kg, though nearing 2000
J/kg further west. This disparity is mainly driven by steepening
lapse rates and drying mid-levels above 700mb per CIRA LPW and RAP
analysis; while profiles are more satuated through depth in the
core of the q-axis from Vermillion to Rapides parish in central
LA.

Divergence is maximized at the entrance of the upper-level jet in
proximity to a weak surface inflection along the pre-frontal
convergence axis/effective cold front across NW LA, extending
northward into AR; while weaker flow exists across the Gulf Coast
proper, the overall confluence through depth (mainly directional)
is resulting in solid deep layer convergence. GOES-E and regional
RADAR mosaic has noted a solid increase in convective coverage and
intensity along the q-axis as well as a few upstream clusters in
SE TX from Houston to the Sabine River. Effective bulk shear is
modest to weak but sufficient for some organized structures and
with deep layer flow from the southwest to the northeast (and
convergent) cell motions may support occasional repeating/training
profiles of these clusters. This is likely to be required to
overcome dry conditions and high FFG values across much of the
area. Still, available moisture and solid flux should result in
efficient rainfall production as updrafts broaden in time, adding
to localized duration and potential for 2" sub-hourly totals.=20

While FFG values are 3-5"/1-3hrs across the area of concern, 12z
HREF neighborhood probability of 3"/6hrs (mainly bolstered
3"/3hrs) is greater than 50% from Brazoria county, TX to West
Feliciana parish, LA with greater than 25% from Sabine River to
St. Landry with greatest potential in Evangeline parish. This
still may only result in widely scattered, low-end instance or two
of localized flash flooding; however there are a few prone urban
centers along that axis where scattered spots of 3-4" may occur.=20
As such, flash flooding is considered possible this afternoon but
mainly after 21z into this evening.=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6n-ejLEnHOG6PoqUDNYEN2ZRXHoBotOpuW1NlaIqP3yng_onEqAHjYo__yKqqnTlUZ12= 1by6IcIG56sR0lS4QZBKW7g$ for graphic product...

ATTN...WFO...HGX...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32279173 31729101 30779125 29389127 29649367=20
29189471 28949525 28999595 29639600 29979574=20
30639496 31499402 31919331 32189273=20

=3D =3D =3D
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AWUS01 KWNH 012212
FFGMPD
LAZ000-020130-

Mesoscale Precipitation Discussion 1110
NWS Weather Prediction Center College Park MD
610 PM EDT Fri Nov 01 2024

Areas affected...South-Central LA

Concerning...Heavy rainfall...Flash flooding possible

Valid 012210Z - 020130Z

SUMMARY...A localized threat of flash flooding will exist through
the early evening hours from slow-moving areas of heavy showers
and thunderstorms.

DISCUSSION...Radar imagery in conjunction with late-day GOES-E IR
satellite imagery shows a general north/south axis of slow-moving
showers and thunderstorms impacting some of the parishes of
south-central LA. The convection is generally aligned in close
proximity to a surface trough and is embedded within a modestly
unstable, but moist environment.

MLCAPE values of 500 to 1000 J/kg are noted along with PWs of 1.75
to 2 inches, and this has been facilitating some rainfall rates of
1 to 2 inches/hour with the stronger convective cores.
Cell-motions though have been rather slow over the last couple of
hours, and this is favoring some locally heavy storm totals.

The loss of daytime heating combined with the convective
overturning process should yield a gradual waning of the diurnal
instability that is pooled across the region, and this will
support an eventual weakening of the axis of convection with
decreasing rainfall rates in time.

Locally as much as an additional 2 to 4 inches of rain will be
possible over the next few hours going through the early evening
hours before the activity weakens. Given some of the rains that
occurred yesterday, these additional totals may support a
localized flash flood threat, but any runoff concerns will mainly
be of the urban variety.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9YEuvS8gngSTPxI8jU8QsFwJP7aQC6OeiLUeUY7GEibCB8aE-UQnYkUMLVM6bQ5XRk0n= U3wXQbzinpsqJ0cilpJ-O7M$ for graphic product...

ATTN...WFO...LCH...LIX...

ATTN...RFC...LMRFC...NWC...

LAT...LON 30929087 30239052 29579057 29469109 30069141=20
30809146=20

=3D =3D =3D
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AWUS01 KWNH 020419
FFGMPD
TXZ000-NMZ000-020930-

Mesoscale Precipitation Discussion 1111
NWS Weather Prediction Center College Park MD
1219 AM EDT Sat Nov 02 2024

Areas affected...eastern NM into the western TX Panhandle

Concerning...Heavy rainfall...Flash flooding possible

Valid 020417Z - 020930Z

SUMMARY...A flash flood threat is expected to increase across
portions of eastern NM into the western TX Panhandle through 09Z.
Rainfall rates of 1-2 in/hr are expected along with 6-hour totals
2-4 inches.

DISCUSSION...Regional radar and GOES East infrared satellite
imagery has shown an increasing coverage of scattered
thunderstorms over southeastern NM, between CNM to just northwest
of CVS since 03Z. Southeasterly low level moisture transport, as
seen on CIRA Layered PW imagery below 700 mb, was contributing to
increasing instability over southeastern NM into the southern TX
Panhandle with 500-1500 J/kg MLCAPE on the 03Z SPC mesoanalysis
co-located with the ongoing storms. 850 mb winds of 30-35 kt were
observed via VAD wind data at KMAF with speed convergence and low
level upslope helping to focus storms.

Back to the west, an eastward moving upper level trough was
observed over the southwestern U.S. with lift out ahead likely to
increase thunderstorm potential across the southern High Plains
through the remainder of the night. The past few runs of the RAP
have supported 30-40 kt 850 mb winds broadening over the Permian
Basin with 40+ kt forecast over the Pecos River Valley in western
TX developing between 06-07Z. Continued moisture advection should
allow MLCAPE to expand as well with 500-1500 J/kg becoming more
widespread across southeastern NM into the western TX Panhandle
through 08Z. While it is not yet clear precisely where, an axis of
low level convergence oriented SW to NE or similar to the mean
steering flow will become better defined tonight, likely allowing
for repeating and occasional training of thunderstorms, capable of
producing 1-2 in/hr rainfall rates. Expectations are for 3 to 6-hr
totals of 2-4 inches which may result in localized flash flooding
through 09Z from portions of southeastern/east-central NM into the
western TX Panhandle.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!57sdomWTh_bBJfA-P_ovTBj3LV_z286AyPyu1zucbTYPqUwm8Vu9YAUUBBZBE_ssU_Tm= MNhlia1Tm2xvM23pReqb1LE$ for graphic product...

ATTN...WFO...ABQ...AMA...LUB...MAF...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 36400148 35040196 33620285 32730365 32320472=20
32910505 34380481 35300412 35980338 36360268=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 020941
FFGMPD
TXZ000-OKZ000-NMZ000-021540-

Mesoscale Precipitation Discussion 1112
NWS Weather Prediction Center College Park MD
540 AM EDT Sat Nov 02 2024

Areas affected...eastern NM into TX Panhandle and western OK

Concerning...Heavy rainfall...Flash flooding likely

Valid 020940Z - 021540Z

SUMMARY...The flash flood threat will continue through 15Z for
eastern NM into the TX Panhandle and western OK with additional
rainfall totals of 2-4 inches. While additional areas of flash
flooding will be likely, coverage is expected to remain isolated
to scattered.

DISCUSSION...0915Z radar imagery showed that an axis of
thunderstorms stretched northeastward from south-central NM into
the TX Panhandle with 2 to 4+ inches of rain estimated via MRMS
since 03Z between ROW and AMA near US 70 in NM and US 60 in TX.
Some recent southeastward bowing was observed to the southeast of
AMA which has reduced training due to the reflectivity axis
falling out of alignment with the mean southwesterly steering
flow. However, greater lift is approaching ahead of an eastward
advancing shortwave trough axis extending SSW from CO into western
NM and southeastern AZ with left-exit and right-entrance ascent
occurring with a pair of developing 100 kt upper level jet streaks
located over northwestern Mexico and the central Plains.

Recent RAP forecasts indicate the 40 kt 850 mb southeasterly LLJ
is at its peak and subtle veering and weakening of the flow is
expected through 15Z across southeastern NM into western TX.
Realignment of the low level convergence axis is forecast to occur
a bit south of its current position as the veering occurs and a
weakness in magnitude occurs over the TX Panhandle near I-40 as
seen in RAP output. As the aforementioned shortwave trough
advances east early this morning some eastward translation to the
low level convergence axis will be possible, allowing for the axis
of training heavy rain (1-2 in/hr rainfall rates) to shift south
and eventually east, out of NM, remaining along the northern edge
of a plume of 500-1500 J/kg MLCAPE.

Additional rainfall totals of 2 to 4 inches (locally higher
possible) are expected in a few locations along the low level
convergence axis but coverage should remain isolated to scattered
across the broader region of eastern NM into the TX Panhandle and
western OK. Therefore, while additional flash flooding will be
likely, it is not expected to be contiguous across the area
through 15Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8w5Z6C4V381UeKdmunju8WV7RMesLDcBAXBV8jgfN_M9UNpTxks9uKQpFHPmwd3v4Caa= rjIw10UnJszxdk9DdDRwkKg$ for graphic product...

ATTN...WFO...ABQ...AMA...LUB...MAF...OUN...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 36620010 36559949 36119924 35569926 34969966=20
34260065 33780198 33370342 33230420 33530458=20
34350398 35300280 36020156=20

=3D =3D =3D
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AWUS01 KWNH 021637
FFGMPD
TXZ000-OKZ000-KSZ000-NMZ000-022200-

Mesoscale Precipitation Discussion 1113
NWS Weather Prediction Center College Park MD
1236 PM EDT Sat Nov 02 2024

Areas affected...Far eastern New Mexico, Texas Panhandle, western
Oklahoma

Concerning...Heavy rainfall...Flash flooding possible

Valid 021635Z - 022200Z

Summary...Convective cells are expected to regenerate along an
outflow boundary and track E/NE through the afternoon. Rainfall
rates in excess of 1"/hr are likely, resulting in axes of 2-3" of
rain with locally higher amounts. This could result in instances
of flash flooding.

Discussion...A longwave trough centered over the Great Basin is
amplifying this morning as evidenced by RAP height falls across
that region. This is resulting in sharpening downstream SW flow
tapping moisture from the Pacific, and PWs of 1.1 to 1.3 inches
have surged into the TX Panhandle, near daily records for early
November. Into this moisture, deep layer lift is increasing as
height falls and divergence downstream of the primary trough axis
increase, and overlap with an impressively coupled jet structure
to produce diffluence aloft. This ascent is being enhanced by
mesoscale lift as low-level southerly flow from south Texas surges
northward on 850mb winds of 20-30 kts, lifting isentropically atop
an outflow boundary evident on the regional radar mosaic. Although
this outflow boundary is progged via hig-res guidance to continue
to shift progressively E/SE, this isentropic ascent should result
in regeneration and training of cells through the aftn.

Rainfall rates in current convection are generally modest, but
MRMS 1-hr rainfall accumulations suggest isolated instances of
1-1.5" of rain in the past hour. These rain rates are somewhat
minimized by a lack of pronounced instability, as the SPC RAP
indicates a sharp MLCAPE gradient from 250-1000 J/kg across the
southern TX Panhandle. As the 850mb LLJ continues from the south
however, there is good agreement that these more robust
thermodynamics will surge northward, reaching 1000-2000 J/kg this
aftn. This should result in increased coverage of rainfall rates
exceeding 1"/hr as progged by both HREF and REFS hourly rain rate probabilities. At the same time, mean 0-6km flow will remain
around 30 kts from the S/SW, suggesting cells that regenerate
along the SW portion of this outflow as it stalls will shift N/NE
and train. This indicates potentially two axes of heavy rainfall:
one along this SW flank where cells repeatedly develop, and a
second maxima into western OK where mean flow is more parallel to
the boundary to enhance training. In both these areas, HREF
neighborhood probabilities for 3"/6hrs reach 40-50%.

Somewhat limiting to the flash flood potential today is
exceptionally dry antecedent conditions reflected by AHPS 30-day
rainfall that is generally less than 25% of normal, leading to
NASA SPoRT 0-40cm soil moisture that is around the 10th
percentile. This suggests that flash flooding should primarily be
isolated the next several hours, but where any of these 1-2"/hr
rates train/regenerate, instances of flash flooding will be
possible.

Weiss

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_sivuCLqYWpUQiub-d02x7hSO9eQHxahb4Oq6eMz4jPq8QnsL-Ao_dEApWdSLfLdFcmJ= C2zuhuEeXPDLEwAeJ1F0xP8$ for graphic product...

ATTN...WFO...ABQ...AMA...DDC...ICT...LUB...MAF...OUN...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 37109866 36999825 36129816 35579814 34769848=20
34139894 33380018 33070197 33050336 33220390=20
33780416 34500396 35100278 35530133 35930028=20
36599923=20

=3D =3D =3D
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AWUS01 KWNH 022101
FFGMPD
TXZ000-NMZ000-030300-

Mesoscale Precipitation Discussion 1114
NWS Weather Prediction Center College Park MD
500 PM EDT Sat Nov 02 2024

Areas affected...Far southeast NM into the Permian Basin and
Rolling Plains of Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 022100Z - 030300Z

Summary...Discrete thunderstorms blossoming across the High Plains
of New Mexico will likely expand in coverage and grow upscale into
clusters through the afternoon. Rainfall rates of 2"/hr or more
are likely, which through several rounds could cause 2-3" of rain
with locally higher amounts. Flash flooding is possible.

Discussion...The regional radar mosaic this afternoon indicates
that discrete thunderstorms, including supercells, have rapidly
developed across southeast NM in the past few hours, and have
expanded into the Permian Basin of Texas. This convection is
blossoming in response to impressive deep layer ascent driven
through PVA downstream of a shortwave lifting across the area
combined with strong upper diffluence within an increasingly
coupled upper jet structure. In the lower levels, 850mb inflow
from the S/SE is lifting isentropically atop a weakening outflow
boundary (which is reflected by a sharp instability gradient),
while concurrently transporting robust thermodynamics northward
characterized by PWs of 0.9-1.2 inches, near the daily record, and
MLCAPE of 1500-2000 J/kg. Rainfall rates within this convection
has been measured by MRMS as high as 1.25-1.5" in the last hour,
leading to modest CREST unit streamflow responses already.

The high-res CAMs appear to generally be under-doing the
convective coverage this aftn, a theme that has been common
through the day. This limits somewhat the confidence in the exact
evolution the next several hours. However, despite coverage and
timing issues with the guidance, they all agree that eventually
thunderstorms will expand and grow upscale into clusters. This
will be supported by a continued increase in deep layer ascent
impinging into persistently elevated thermodynamics as the
low-level flow remains. This should result in thunderstorms that
intensify, supporting rainfall rates which have a 10-20% chance
(HREF) and 30% chance (REFS) of exceeding 2"/hr through the aftn
and into the evening. Mean 850-300mb winds are expected to remain
progressive at 30 kts from the SW, but despite this, as storms
organize through 0-6km bulk shear of 40-50 kts, intense rain rates
through short-term training could result in maximum rainfall of
2-3" with locally higher amounts.

Far southeast NM, the southern Permian Basin, and the southern Cap
Rock have all been very dry the past 7 days, but AHPS rainfall
departures are well above normal north of there. This has lowered
3-hr FFG to just 1-1.5" across the more saturated soils. As
convection expands and organizes, it could move across these more
sensitive soils, leading to potential instances of flash flooding
into the evening.

Weiss

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9fZYSOBsfKMWwBrnJl09Fu18l1wFuP18o99ZBaEdAOste4iYZ2sOyVBwb40f3S14J5VE= a50tob3cOhtjGvoTB6Ao27U$ for graphic product...

ATTN...WFO...ABQ...AMA...LUB...MAF...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 35150214 35090174 35030081 34479995 33529946=20
32739960 32020063 32010225 32340369 32760419=20
33450422 34390390 35010320=20

=3D =3D =3D
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AWUS01 KWNH 030424
FFGMPD
MOZ000-TXZ000-OKZ000-KSZ000-030930-

Mesoscale Precipitation Discussion 1115
NWS Weather Prediction Center College Park MD
1224 AM EDT Sun Nov 03 2024

Areas affected...northwestern TX into central/northeastern OK, far
southeastern KS, far southwestern MO

Concerning...Heavy rainfall...Flash flooding likely

Valid 030422Z - 030930Z

Summary...Areas of flash flooding are expected to develop in a
zone from northwestern TX into central OK and northeastern OK
through 09Z. Some spillover into southeastern KS and southwestern
MO may occur as well. Rainfall rates of 1-2 in/hr and areas of
training may support localized totals over 4 to 5 inches through
10Z.

Discussion...Regional radar imagery at 04Z showed an eastward
propagating line of thunderstorms tracking across the southern TX
Panhandle, just east of the Caprock Escarpment. Additional showers
and thunderstorms were noted across the Red River into much of OK.
All of this activity was located near or northwest of a remnant
outflow boundary which extended from near MAF to RPH in TX, then
northeastward into OK between TUL and OKM. SPC mesoanalysis data
indicated MLCAPE values were 500-1500 J/kg along and south of the
outflow boundary, while CAPE dropped off significantly to the
north of the outflow. 850 mb winds of 35-45 kt from the south were
present over west-central TX into central/eastern OK, overrunning
the outflow and forcing convection. Large scale lift was present
over the region out ahead of a longwave trough axis moving through
the southwestern U.S. and within the divergent and diffluent
left-exit region of a prominent 110-130 kt upper level jet max
streaking across northern Mexico into southwestern TX.

Broad forcing ahead of the eastward moving upper level trough over
the Southwest will allow southerly low level winds to maintain and
locally strengthen over TX/OK tonight, continuing overrunning
thunderstorms north of the outflow. The outflow boundary itself is
expected to become more diffuse with time over OK but stay better
defined over TX, to the south of the eastward advancing line.

Despite the forward progression of the convective line east of the
Caprock, mean southwesterly steering flow will align with the axis
of low level forcing, whether it be the outflow boundary or
convective lines near/north of the outflow to support training.
Rainfall rates of 1-2 in/hr (locally higher) are likely to develop
within areas of training with multiple hours of heavy rain
possible over a given location.

Despite mostly dry ground conditions from ongoing drought, high
rainfall rates over a short period of time are expected to
overwhelm soils and support areas of flash flooding, with
localized totals over 4 to 5 inches possible. The flash flood risk
will be enhanced if these higher rates overlap with urban
corridors, including the Oklahoma City and/or Tulsa metro.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-ZkYQZkpltbcbSITwUyr7lRNxPu9ZszvZsBo8UfV0cs4d_wCRn8s1Xvo6_3ly43CIlMl= xcbEvFbqWUm700Ae-eRUdrY$ for graphic product...

ATTN...WFO...FWD...ICT...LUB...MAF...OUN...SGF...SJT...TSA...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 37399543 37189435 36199484 35119577 33759736=20
33349826 32540053 32530124 32890105 33820040=20
34779997 36239789=20

=3D =3D =3D
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AWUS01 KWNH 030931
FFGMPD
TXZ000-OKZ000-031500-

Mesoscale Precipitation Discussion 1116
NWS Weather Prediction Center College Park MD
430 AM EST Sun Nov 03 2024

Areas affected...northern TX into southern OK

Concerning...Heavy rainfall...Flash flooding possible

Valid 030929Z - 031500Z

Summary...An axis of training heavy rain is expected to impact
portions of northern TX into southern OK through 15Z with rainfall
rates of 1 to 2+ in/hr. Rainfall totals of 2 to 4+ inches are
expected through 15Z along with possible flash flooding.

Discussion...Looping regional radar imagery through 09Z showed a
QLCS progressing eastward across OK at roughly 40-50 kt but the
southwestern flank of this convective line has largely stalled
across northwestern TX, between US 180 and US 380 to the north of
Abilene. Area VAD winds at 850 mb showed 40-45 kt from the south
across central to western TX, overrunning the rain-cooled airmass
where 1000 to 2000+ J/kg MLCAPE was present along and south of the
outflow boundary (per 09Z SPC mesoanalysis). In addition to the
low level forcing in place, flow aloft was diffluent and
divergent, within the left exit region of a RAP-estimated 110-120
kt upper level jet max crossing Big Bend NP.

Despite the typical diurnal cycle favoring weakening of the low
level jet through 15Z, RAP forecasts suggest only slight weakening
of the 850 mb winds (into the 30-40 kt range) as a shortwave
trough axis over the southern AZ/NM border translates eastward
this morning. However, infrared cloud tops have been warming
across northwestern TX over the past hour, perhaps due to a
combination of the intrusion of dry air aloft as seen on Layered
PW imagery and weakening moisture flux.

Despite the recent weakening, a flash flood threat will remain
across the Red River Valley over the next few hours as areas of
training will likely persist into the mid-morning hours with storm
motions parallel to the low level axis of forcing. The threat for
training and 1 to 2+ in/hr rates is expected to shift ENE across
the Red River into portions of southern OK through 15Z along with
additional rainfall totals of 2 to 4 inches (locally higher).
Flash flooding will continue to be possible over the next few
hours with an expected weakening of rainfall intensity and
training potential toward the end of the MPD valid time (13-15Z).

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8SWgZZWagO723T5X43F4I2cxNKzGTFEXBk3v5gSAT5k1JR2e6gQC8jPncN_CMnario-l= 9iI12I6J3j0vcbkRePX4w9A$ for graphic product...

ATTN...WFO...FWD...OUN...SHV...SJT...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON 35269523 35099451 34269451 33389623 32939780=20
32710002 33489970 34339837 34829718 35079643=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 031018
FFGMPD
MOZ000-ARZ000-OKZ000-KSZ000-031435-

Mesoscale Precipitation Discussion 1117
NWS Weather Prediction Center College Park MD
517 AM EST Sun Nov 03 2024

Areas affected...southwestern MO, southeastern KS, northwestern
AR, northeastern OK

Concerning...Heavy rainfall...Flash flooding possible

Valid 031016Z - 031435Z

Summary...A localized occurrence or two of flash flooding will be
possible across southeastern KS/northeastern OK into the Ozarks
through 15Z. While an overall weakening trend in flash flood
potential is expected over the next few hours, rainfall rates of
1-2 in/hr through training may overlap hydrologically sensitive
locations, resulting in runoff issues.

Discussion...10Z radar/satellite imagery showed an MCS tracking
across eastern OK with a convectively induced vorticity max (MCV)
inferred across east-central OK. South of the MCV, a convective
line was rapidly advancing eastward, limiting the threat for
short-term flash flooding over eastern OK. Farther north, rainfall
was more stratiform in nature with embedded convective elements.
Strong lift was occurring across eastern KS/OK within a coupled
upper level jet exit/entrance region supporting a divergent and
diffluent regime aloft. Instability was limited however, with
MUCAPE values of ~500 J/kg or less per 09Z SPC mesoanalysis data.

Expectations are for the MCV and associated areas of heavy rain
with embedded training to track toward the northeast over the next
2-4 hours. While instability is forecast to remain limited across
northeastern OK/southeastern KS into adjacent areas of MO/AR,
strong dynamic lift ahead of the MCV and within the favorable divergent/diffluent pattern aloft may favor brief instances of SW
to NE training within the unidirectional SW flow. Rainfall rates
of 1 to 2 in/hr will be possible along with an additional 2 to 3
inches of rain (locally higher possible) through 15Z. Overlap of
these heavier rainfall rates may overlap with urban areas or an
estimated 4-6 inches of rain which impacted the I-44 corridor in
northeastern OK over the past 12 hours, to generate localized
flash flooding. However, with time, weakening of rainfall
intensities are expected with increased forward progression and a
less favorable thermodynamic environment.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5Cub1FPd4NFK64jn8GQ1EqyYez2ipYeVqsMrLaYvdXwAwh8_sCiDYnA4hlw5Mdglsc-R= f6cTdO_OJbAdFRZ6fbLpod0$ for graphic product...

ATTN...WFO...EAX...ICT...SGF...TOP...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC...

LAT...LON 38639458 38499366 37579339 35519420 35369575=20
36089627 37589583=20

=3D =3D =3D
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AWUS01 KWNH 031956
FFGMPD
TXZ000-OKZ000-040200-

Mesoscale Precipitation Discussion 1118
NWS Weather Prediction Center College Park MD
255 PM EST Sun Nov 03 2024

Areas affected...central and southern OK...North TX

Concerning...Heavy rainfall...Flash flooding likely

Valid 032000Z - 040200Z

Summary...Localized 2-4" short term totals likely to result in
isolated to scattered instances of flash flooding through the
afternoon.

Discussion...Convective coverage is increasing this afternoon
across North TX and southern OK, the most intense of which
initiated in the vicinity of the dry line this morning (and is
quickly organizing into a distinct bow echo). This region is
encompassed within a large warm sector and associated low-level
convergence, and instability is once again building after the
passage of an organized MCS overnight. The mesoscale environment
is characterized by ML CAPE of 1000-2000 J/kg (except over
northeast OK, though continued warm air advection and isentropic
lift will change that over the next several hours), PWATs of
1.4-1.7 inches (near record levels, per OUN sounding climatology),
and effective bulk shear of 45-55 kts.

Continued building instability within this favorable environment
will support increased coverage and intensity of convection into
the evening. This is especially the case given the upper-level
support, as upper-level diffluence is even more impressive than
the low-level convergence (with a phased northern and southern
stream allowing for idealized left-exit region of a sub-tropical
jet streak and right-entrance region of a polar jet streak). Given
the prior rainfall over the past 24 hours (locally up to 3-6"+
over much of OK, per MRMS estimates), antecedent conditions will
be more supportive of excessive rainfall with this next round of
storms.

Hi-res CAMs are in relatively good agreement with convective
evolution, suggesting the potential for localized 2-4" totals over
the next 3-6 hours (per HREF probability-matched mean QPF). While
fast storm motions should generally limit hourly totals to 1.5" or
so (at least through 02z), localized repeating/training of these
rates should support those advertised 3-6 hour totals. The
corresponding Flash Flood Guidance (FFG) are on the order of only
1.5-3.0" (given the aforementioned antecedent conditions), so
isolated to scattered instances of flash flooding are considered
likely.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9GoAKxlm-gjyqehAGTrt7i73DGblpUjZlVoVP1BmPCr1TKxp0RuyDh2p2TxivO--G7yp= S_OTBIUEhW8e9zT53YjaygU$ for graphic product...

ATTN...WFO...FWD...OUN...SJT...TSA...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 36849700 36489552 34709566 33309664 32669743=20
32449864 32149960 32259996 33489973 34559997=20
35109963 35689850=20

=3D =3D =3D
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AWUS01 KWNH 040001
FFGMPD
MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-040559-

Mesoscale Precipitation Discussion 1119
NWS Weather Prediction Center College Park MD
701 PM EST Sun Nov 03 2024

Areas affected...in and near portions of eastern OK, AR, and
southern MO

Concerning...Heavy rainfall...Flash flooding likely

Valid 032359Z - 040559Z

Summary...Training showers and thunderstorms over saturating soils
and area terrain are expected to lead to scattered instances of
flash flooding through 06z. Hourly rain totals to 2.5" with local
totals to 5" are expected over that time frame.

Discussion...An upper trough crossing the southern Rockies is
causing a broad area of divergence aloft across portions of the
southern Plains and Mid-South. An effective front, part synoptic
scale and part outflow boundary, extends from a low near the Red
River of the South across southern and eastern AR into the
Bootheel of MO. Along and north of the boundary a broad area of
showers and thunderstorms with heavy rainfall exists, with a
slight break in easternmost OK. Precipitable water values are
near 2" per GPS data. MU CAPE of 500-2000 J/kg exists near the
convection. Effective bulk shear is near 60 kts, more than
sufficient for mesocyclone development. The mean flow is out of
the south-southwest at ~60 kts, with some veering seen in the
low-levels. This is helping to support training convective bands.

The mesoscale guidance broadly supports heavy rainfall in the
region, with high chances of 3"+ across southeast OK, northwest
AR, and some of southern MO. The two areas of heavy rainfall are
expected to merge with a potential increase in intensity as warm
air advection increases MU CAPE into the region over the next
several hours due to strengthening 850 hPa inflow from the Gulf of
Mexico. Some veering to the low-level flow should continue
eastward progression, but also increase the likelihood for cell
training as the flow becomes more unidirectional with height.=20
Given the ingredients available, hourly rain totals to 2.5" with
local totals to 5" are expected over the next several hours, which
would prove too much for saturating soils across portions of
eastern OK and southwest AR. Such rainfall would be problematic
in the terrain of the Ozarks as well. Given the above, chose the
flash flooding likely category as scattered instances of such are
expected through 06z.

Roth

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5roeQX5FJkgHaqNiYugR-h_BHSGYwzeRuOBttKnx0vGVCyXi9xIkJ9nsI1XZrgAJKz2O= qlqQtvL4M1H9-6pU3n9apao$ for graphic product...

ATTN...WFO...FWD...ICT...LSX...LZK...MEG...OUN...PAH...SGF...
SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...WGRFC...NWC...

LAT...LON 37909406 37639210 37599025 37038960 34749105=20
33719305 33079646 33279801 34459757 34859724=20
36089668 37419605 37489496=20

=3D =3D =3D
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AWUS01 KWNH 040612
FFGMPD
MOZ000-ARZ000-OKZ000-041030-

Mesoscale Precipitation Discussion 1120
NWS Weather Prediction Center College Park MD
111 AM EST Mon Nov 04 2024

Areas affected...eastern OK, northwestern AR, southern MO

Concerning...Heavy rainfall...Flash flooding possible

Valid 040610Z - 041030Z

Summary...Periods of training convection may result in a few areas
of flash flooding from eastern OK into northwestern AR and
southern MO through 11Z. 2 to 4 inches of rain is expected where
training sets up.

Discussion...A composite outflow boundary was analyzed at 06Z from
the eastern MO/AR border into central AR, eastern OK and then
southwestward across the Red River between Denison and Wichita
Falls, TX. Elevated thunderstorms were occurring to the north of
the outflow with an eastward advancing contiguous convective line
from central MO into northwestern AR. Convective line progression
was stalled or retrograding slightly to the north over
northwestern AR and a fragmented/broken axis of thunderstorms
extended westward from northwest AR into central OK with
individual cell motions off toward the NNE but better organization
was lacking over OK. Southerly low level winds were overrunning
the boundary supporting the continued regeneration of
thunderstorms, acting on 1000-2000 J/kg MLCAPE along and south of
the outflow boundary in eastern OK. While the better 850 mb flow
was located ahead of the advancing convective line in MO/AR, 30 to
50 kt of S to SSW 850 winds were reported via VAD wind data to the
south of the outflow from eastern OK into northern TX.

The eastward advancing convective line in MO/northern AR is
expected to continue pushing off toward the east but back to the
west in OK, the outflow boundary is expected to continue a modest
retreat northward within deep-layered S to SW flow ahead of a
longwave trough over the Four Corners region. Isentropic ascent
across the composite outflow boundary will likely maintain some
degree of convective regeneration over central to eastern OK into
far western AR through 11Z. While not forecast to be widespread,
instances of training will occur where convective orientation
aligns with the deeper layer SSW steering flow. Training will
support rainfall rates of 1-2 in/hr, some of which will overlap
with saturated top layer soils given recent heavy rainfall over
the past 24-36 hours.

Areas of training are expected to be transient and scattered
across the region overnight. Recent hires guidance does not have a
good handle on the progression and timing of convection compared
to recent radar trends, so their forecast coverage of 3 to 6
inches through 12Z may be overdone. Nonetheless, 2-4 inches in a
few locations is still expected which may lead to a few areas of
flash flooding.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_BVvGhDVAZ2B8FPWrhcuMZmLwdopOzAjWuA1YbeFKJeLubKtRiA7uDVJjmgLGPeBsVcU= yFkojwnwl-Z6p-Gw2gLn5lU$ for graphic product...

ATTN...WFO...LZK...OUN...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC...

LAT...LON 37399216 37059129 36369142 35739212 35039398=20
34879485 34829630 34919710 35249739 35859701=20
36109634 36449520 36969385=20

=3D =3D =3D
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AWUS01 KWNH 041056
FFGMPD
ILZ000-MOZ000-ARZ000-041545-

Mesoscale Precipitation Discussion 1121
NWS Weather Prediction Center College Park MD
555 AM EST Mon Nov 04 2024

Areas affected...northern AR into south-central/southeastern MO,
southwestern IL

Concerning...Heavy rainfall...Flash flooding possible

Valid 041052Z - 041545Z

Summary...Areas of training heavy rain will continue to pose a
possible threat for flash flooding across parts of northern AR
into south-central/southeastern MO through 15Z. Portions of
southwestern IL may also see impacts. Rainfall rates of 1-2 in/hr
(locally higher) should be expected.

Discussion...10Z surface observations showed an elongated outflow
boundary extended southwestward from the southern IL/MO border
into northwestern AR and southeastern OK. Training and repeating
rounds of thunderstorms were occurring along and just north of the
outflow boundary from northwestern AR into southern MO, with
MRMS-derived peak rainfall rates of 1.0-1.5 in/hr. Area VAD wind
plots of 850 mb winds showed 40-50 kt in place from Fort Smith to
Memphis, overrunning the boundary and allowing training of heavy
rainfall echoes given similarly oriented steering flow from the
SSW. There was a gradient in MLCAPE across AR, with 10Z SPC
mesoanalysis data showing 1500 j/kg along the OK/AR border,
weakening to the east with less than 500 J/kg along the AR/TN
border, with elevated instability only marginally greater to the
north.

There is little change expected to the regional pattern in place
over the next 3-6 hours, with 850 mb winds of 40-50 kt forecast by
the RAP to continue through 15Z, along with similar instability
and broad/weak diffluent flow aloft. While convective overturning
may moderate current instability values a bit with time,
orographic ascent will enhance low level lift across the southern
Ozark Plateau. Expectations are for occasional areas of training
to setup from northern AR into south-central and southeastern MO,
producing 1-2 in/hr rainfall rates as these relatively strong low
level winds overrun the well-defined outflow boundary in place.
Flash flooding will remain possible for at least another few hours.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6esZksp20i22w9zNGb6Tbxuho3rHSU6729EsWhE658bozFtJlDZuFfNE3fjM5uMtoDny= _pJLFzSNVC-N8gRcVVXbKYM$ for graphic product...

ATTN...WFO...LSX...LZK...MEG...PAH...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...NWC...

LAT...LON 38518998 38458936 38288912 37378937 36069137=20
35239281 34989325 34979377 35129412 35189422=20
35629435 36219404 36999323 38339078=20

=3D =3D =3D
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AWUS01 KWNH 041535
FFGMPD
ILZ000-MOZ000-ARZ000-042133-

Mesoscale Precipitation Discussion 1122
NWS Weather Prediction Center College Park MD
1034 AM EST Mon Nov 04 2024

Areas affected...Northern AR...South-Central to Southeast
MO...Southwest IL

Concerning...Heavy rainfall...Flash flooding likely

Valid 041533Z - 042133Z

SUMMARY...Additional rounds of heavy showers and thunderstorms
which will occasionally repeat over the same area will continue to
foster areas of flash flooding heading into the afternoon hours.

DISCUSSION....GOES-E IR satellite imagery in conjunction with
dual-pol radar shows a fairly large broken area of heavy showers
and thunderstorms impacting portions of northern AR through
southeast MO and a small part of southwest IL. The activity
continues to be strongly influenced by enhanced warm air
advection/isentropic ascent and moisture transport across the
region with deep layer southerly flow in place out ahead of a deep
layer trough/closed low gradually ejecting east out of the
southern Rockies.

A southerly low-level jet of 40 to 50 kts in the 850/925 mb layer
is noted in the latest VWP data across central to northern AR and
across southeast MO and southern IL which is acting as a conduit
for the poleward transfer of Gulf of Mexico moisture. PWs across
the region are locally as high as 1.75 inches which are on the
order of 2 to 3+ standard deviations above normal for this time of
the year. This anomalous moisture environment will continue to
favor a well-defined excessive rainfall threat with enhanced
rainfall rates given the warm air advection and proximity of at
least modest instability.

MUCAPE values are on the order of 500 to 1000 J/kg up across
northern AR through southeast MO and this is supporting a largely
elevated convective environment at this time. Some increase in
instability is expected going through mid-afternoon and this
should favor some increase in the rainfall rates which will be
capable of reaching 1 to 2 inches/hour with the stronger storms.

Going through the mid-afternoon hours, additional rainfall totals
of 2 to 4 inches will be possible, with the heaviest totals most
likely over south-central to southeast MO based on the latest 12Z
HREF guidance. The very wet/saturated antecedent conditions that
are in place coupled with the arrival of additional rounds of
heavy rain over the same area will continue to promote additional
areas of flash flooding with locally considerable runoff concerns.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6GXloCu9o8ZI23AqUpAPdrA1vlbzXXVEvhxpVyv55LOvfXK-763HvBckSdXnu4BCvxz1= AIF6aQnKNba119zkyBfpiPA$ for graphic product...

ATTN...WFO...LSX...LZK...MEG...PAH...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...NWC...

LAT...LON 38619040 38578962 37988941 37109001 36469070=20
35479239 35129354 35689421 36669363 37929201=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 041722
FFGMPD
MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-042320-

Mesoscale Precipitation Discussion 1123
NWS Weather Prediction Center College Park MD
1221 PM EST Mon Nov 04 2024

Areas affected...Eastern OK...Northwest AR...Far Southeast
KS...Southwest MO

Concerning...Heavy rainfall...Flash flooding likely

Valid 041720Z - 042320Z

SUMMARY...Heavy showers and thunderstorms will gradually become
more concentrated and organized by mid to late afternoon across
eastern OK which will also impact portions of northwest AR, far
southeast KS and southwest MO by this evening. Locally wet
antecedent conditions and the additional rainfall will likely
result in areas of flash flooding.

DISCUSSION...A strong deep layer trough and associated closed low
ejecting out of the southern Rockies will be interacting with a
very moist and increasingly unstable airmass pooling north across
the Red River Valley of the South, and will be setting the stage
for a more organized and concentrated convective outbreak by mid
to late afternoon across areas of eastern OK and eventually
advancing into far southeast KS, northwest AR and southwest MO by
early this evening. Many of these areas have already seen heavy
rainfall over the last couple of days, and the arrival of
additional rounds of strong convection and heavy rainfall rates
will promote a likelihood for seeing additional flash flooding
concerns.

The latest surface analysis shows a cold front gradually shifting
east across the Red River Valley of the South with a wave of low
pressure seen crossing through central OK. Meanwhile, a warm front
is noted out ahead of this stretching across eastern OK and into
northwest AR. MLCAPE values of 1500+ J/kg have already pooled up
across southeast OK and far western AR with 40 to 50+ kts of
effective bulk shear in place given the stronger wind fields
arriving ahead of the upper trough. Already the latest GOES-E
visible satellite imagery shows a substantial amount of cloud
street activity over eastern OK and this is suggestive of
increasing boundary layer instability with a strong low-level jet.

CIRA-ALPW data shows notably concentrated moisture in the
low-levels of the column with enhanced layered vapor transport
(LVT) seen extending up through northeast TX, eastern OK and
western AR. This is being facilitated by a southerly low-level jet
of 40 to 50 kts. This moisture transport coupled with the
instability and shear should favor an environment conducive for
enhanced rainfall rates.

As height falls associated with the upper trough arrive this
afternoon, a combination of DPVA/divergent flow aloft and the
favorable thermodynamic and kinematic environments will support
the development of more focused/organized convection which will
likely include embedded supercell activity. Rainfall rates will be
capable of reaching 1.5 to 2.5 inches/hour with the more organized
cells, and as convection grows upscale this afternoon and early
this evening, some additional storm totals may reach 2 to 4 inches
which is supported by the 12Z HREF guidance.

The wet antecedent conditions coupled with these additional rains
will likely result in more concerns for flash flooding by late
afternoon or early this evening.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!95vqJy86OmPuqhXcuLKln84-u1AkcPL89a_zxTnBQgrSnqC1KOAuuJfHhfXvAydRDGQd= VD5W9jBLYO2dYZASnpyjkfU$ for graphic product...

ATTN...WFO...FWD...ICT...LZK...OUN...SGF...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC...

LAT...LON 37609449 37279352 36209347 34739408 33879507=20
33969662 34659700 35739666 36809615 37439530=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 042146
FFGMPD
TXZ000-OKZ000-050345-

Mesoscale Precipitation Discussion 1124
NWS Weather Prediction Center College Park MD
445 PM EST Mon Nov 04 2024

Areas affected...Central to Northeast TX

Concerning...Heavy rainfall...Flash flooding possible

Valid 042145Z - 050345Z

SUMMARY...Showers and thunderstorms with very heavy rainfall rates
may produce some isolated to scattered instances of flash
flooding, and especially within the more urbanized corridors
heading through the evening hours.

DISCUSSION...An upper-level trough and associated closed low
continues to eject gradually across the southern Rockies which is
driving a cold front well to the east across the southern Plains.
This front has been crossing through central and northern TX this
afternoon and is bumping up against a very moist and unstable
environment that is characterized by MLCAPE values of 1500 to 2500
J/kg and PWs of 1.5 to 1.75 inches.

A major driver of the moisture and instability transport continues
to be a well-defined low-level jet that is locally reaching 40 to
50 kts, and the latest GOES-E GeoColor satellite imagery shows a
substantial amount of cloud street activity ahead of the
approaching cold front.

Increasingly divergent flow aloft associated with the ejecting
height falls/DPVA will favor convection along and just ahead of
the cold front becoming more organized and widespread heading
through the evening hours, and especially with the strongly
favorable thermodynamic environment. A substantial level of
effective bulk shear is in place that will be conducive for a
combination of multicell and supercell activity that aside from
severe weather hazards will be conducive for producing high
rainfall rates.

The convective mode along and ahead of the front will likely
attain a QLCS mode in time, and with a southward extension that
will eventually include areas of south-central TX including
eastern portions of the Hill Country by later this evening.
Rainfall rates may reach as high as 2 inches/hour with the
stronger convective cores heading through the evening hours.

Generally the antecedent conditions across central to northeast TX
are on the dry side, but the convective evolution over the next
several hours will be conducive for some 2 to 4 inch rainfall
amounts which may end up being locally higher if any cell-training
or cell-merger activity takes place. Some isolated to scattered
instances of flash flooding will be possible and especially within
the more urbanized corridors.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9Gd0Zmw3lA-9sBhCOOjiKxYBkmKijk3RdpC194yF9odQUX4QTtkQgry53i9TbbTl3VT0= oH7y1s-uQMzHDGJeGR5JCYg$ for graphic product...

ATTN...WFO...EWX...FWD...HGX...OUN...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON 33969545 33599491 32899484 31539550 30419629=20
29569746 29649834 30429842 31859741 33629645=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 042156
FFGMPD
MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-050355-

Mesoscale Precipitation Discussion 1125
NWS Weather Prediction Center College Park MD
455 PM EST Mon Nov 04 2024

Areas affected...Eastern OK...West-Central to Northwest
AR...Southwest MO

Concerning...Heavy rainfall...Flash flooding likely

Valid 042155Z - 050355Z

SUMMARY...Well organized bands of showers and thunderstorms will
continue through the evening hours. Heavy rainfall rates and wet
antecedent conditions are expected to result in scattered to
numerous areas of flash flooding this evening. Some locally
significant and life-threatening impacts will be possible.

DISCUSSION...A strong deep layer trough and associated closed low
continues to advance very slowly across the southern Rockies and
toward the southern High Plains. A strong cold front associated
with this continues to gradually advance eastward with a notably
unstable and highly sheared environment focused out ahead of it.
Strong and well organized bands of convection are seen in GOES-E
IR satellite imagery and dual-pol radar focusing across eastern OK
with separate clusters of convection noted across portions of
western AR and southwest MO.

MLCAPE values ahead of the cold front over eastern OK and western
AR are as high as 1500 to 2500 J/kg, and this instability axis has
been gradually nosing up into areas of southwest MO over the last
couple of hours. A southerly low-level jet of 40 to 50 kts remains
in place across the region, and this will drive strong moisture
and instability transport through the evening hours as the cold
front off to the west approaches the region.

Strong and well organized bands of convection including some
occasional supercell structures are expected to result in heavy
rainfall totals this evening over areas of especially east-central
OK, northwest AR and southwest MO. This is where there will be
concerns for some cell-training and rainfall rates capable of
reaching 1.5 to 2.5 inches/hour. PWs are already running locally
near 1.75 inches and with the enhanced instability/shear profiles
and moisture transport across the region, the rates should be
efficiently high.

Additional rainfall amounts by late this evening of 2 to 4 inches
are expected, with isolated heavier amounts of 5+ inches possible
where areas of cell-training are maximized. The experimental WoFS
and latest HREF guidance generally supports these amounts on the
mesoscale level. Given the additional rainfall, and the wet
antecedent conditions, scattered to numerous areas of flash
flooding are likely. Locally significant and life-threatening
impacts will be possible this evening which will include some of
the more urbanized locations.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5RRnrqCtmH0jJ4PgRf_q-XgyLodShvGl6aZ6DOvFjKTQ3fTMI8NB4UVokbbGdD88Zpzr= NR3o-GtEtqJFuY-TY8SZG7s$ for graphic product...

ATTN...WFO...FWD...LZK...OUN...SGF...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC...

LAT...LON 37939289 37459231 36839228 35819269 34899326=20
34019406 33649469 33709514 33979596 34249607=20
35289564 36289523 37209471 37819406=20

=3D =3D =3D
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AWUS01 KWNH 042221
FFGMPD
ILZ000-MOZ000-050420-

Mesoscale Precipitation Discussion 1126
NWS Weather Prediction Center College Park MD
520 PM EST Mon Nov 04 2024

Areas affected...Central and Eastern MO...West-Central and
Southwest IL

Concerning...Heavy rainfall...Flash flooding likely

Valid 042220Z - 050420Z

SUMMARY...Additional rounds of heavy showers and thunderstorms
going well into the evening hours will maintain strong concerns
for instances of flash flooding.

DISCUSSION....GOES-E IR satellite imagery in conjunction with
dual-pol radar shows broken areas of heavy showers and
thunderstorms arriving across west-central to southwest MO with
separate areas of convection noted farther east across portions of
central and eastern MO. The activity continues to be strongly
influenced by strong warm air advection/isentropic ascent and
moisture transport across the region. This continues to be
facilitated by persistent and strong deep layer southerly flow out
ahead of a deep layer trough/closed low edging out into the
southern High Plains from the southern Rockies.

A southerly low-level jet of 40 to 50 kts remains in place and is
nosing up across much of western AR and southern MO, and this is
overrunning a warm front seen lifting north currently through
northwest AR and southern MO. PWs across the region are locally as
high as 1.75 inches which again are on the order of 2 to 3+
standard deviations above normal for this time of the year. This
will continue to favor an environment conducive for enhanced
rainfall rates going through the evening hours and especially with
the low-level jet yielding a gradual and steady increase in
instability.

MLCAPE values have risen to 500 to 1000 J/kg across all of
southern MO, with values locally approaching 1500 J/kg across
southwest MO. This coupled with strong forcing and shear
parameters going through the evening hours will strongly support
additional bands or clusters of heavy showers and thunderstorms.
Areas of central and eastern MO north of the warm front will have
concerns heading through this evening for repeating rounds of
convection and cell-training that will yielding enhanced rainfall
totals. Some of this may also impact areas of west-central to
southwest IL.

These additional rains will be on top of the earlier rainfall and
will be falling on already very sensitive soil conditions. The
latest HRRR guidance and HREF footprint suggests additional
rainfall amounts through late this evening of 2 to 4 inches with
isolated heavier amounts not out of the question. Given the
environment, these rains are expected to result in additional
instances of flash flooding.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8XP-KcNTm18TTlniNf-nojK7YjFoVdX-mOMZdeZe4gtlEdupk7aUq7NtbsJxcMKEG219= bY51OK6YzlSrLwojO64KCMM$ for graphic product...

ATTN...WFO...EAX...ILX...LSX...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...NWC...

LAT...LON 39809122 39759030 39488971 39088952 38648982=20
38189049 37799129 37159206 37529232 37949298=20
37939403 38569395 39029351 39409287 39599236=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 050356
FFGMPD
ILZ000-MOZ000-ARZ000-TXZ000-OKZ000-050915-

Mesoscale Precipitation Discussion 1127
NWS Weather Prediction Center College Park MD
1056 PM EST Mon Nov 04 2024

Areas affected...northeastern TX/southeastern OK into western AR
and central/southern MO

Concerning...Heavy rainfall...Flash flooding likely

Valid 050354Z - 050915Z

SUMMARY...A slow moving axis of heavy rain will result in
continued flash flooding from northeastern TX/southeastern OK into
western AR and central/southern MO through 09Z. Rainfall rates of
1-2 in/hr should result in an additional 2-4 inches of rain
(locally higher), atop saturated soils.

DISCUSSION....03Z radar imagery and surface observations placed a
SW to NE axis of thunderstorms from northeastern TX into
northwestern AR and southern/eastern MO, out ahead of a cold front
located west of the convective line. The convective line was
nearly coincident with the front over northeastern TX, but was
located increasingly east of the cold front into AR/MO as one
moves north, located along an outflow boundary. The orientation of
the convective axis matching the mean southwesterly steering flow
has allowed for training with MRMS-derived rainfall rates of 1 to
locally over 2 in/hr since 00Z. 03Z SPC mesoanalysis data showed
MLCAPE was only about 500 J/kg along and immediately ahead of the
convective line/outflow boundary but anomalous precipitable water
values of 1.7 to 1.9 inches and divergence aloft within the
right-entrance region of a 110-130 kt jet max over the
middle/upper MS River Valley was leading to enhanced lift and
efficient rainfall production.

Infrared satellite imagery showed a gradual warming of cloud tops
over the region since 00Z, but occasional bursts of colder cloud
tops continued to occur. Following trends in radar imagery over
the past few hours and understanding that height falls downstream
of a slow moving upper trough axis over the TX Panhandle will only
gradually push off to the east through 09Z, the axis of heavy rain
is only expected to slowly shift eastward. There could be
relatively faster movement with the rainfall axis located in MO
compared to locations farther south, but regeneration and training
of thunderstorms to the southwest could allow for a prolonged
duration of heavy rain for some locations as cells move back to
the north. Some gradual weakening of CAPE is anticipated through
the night but strong forcing for ascent should maintain periods of
high rainfall rates with 1 to 2 in/hr (locally higher) gradually
translating toward the east through 09Z. Given heavy rain which
has impacted northwestern AR over the past 48 hours, and the
sensitive terrain of the Ozarks, additional flash flooding will be
likely, with locally significant impacts possible through 09Z.
Additional totals of 2 to 4 inches (locally higher) can be
expected, with northern AR into southern MO possibly seeing the
greatest additional rainfall over the next few hours.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9JlLNBDATprWAX3QV5Kjx_voQ0HDTuZk7kisiL1bP31h81pfjBnBFO9rUhxzWVZ7DcIQ= vx-V4-OoXeJgJaigPaqrzQw$ for graphic product...

ATTN...WFO...FWD...LSX...LZK...PAH...SGF...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...WGRFC...NWC...

LAT...LON 39069025 38559023 36609106 34879217 33149390=20
32219511 32499587 33739551 35329445 36869299=20
38639153=20

=3D =3D =3D
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AWUS01 KWNH 050402
FFGMPD
TXZ000-050800-

Mesoscale Precipitation Discussion 1128
NWS Weather Prediction Center College Park MD
1101 PM EST Mon Nov 04 2024

Areas affected...Central Texas

Concerning...Heavy rainfall...Flash flooding likely

Valid 050400Z - 050800Z

SUMMARY...Flash flooding likely as storms producing up to 3 inch
per hour rainfall rates train over/near San Antonio and Austin.
Urban flash flooding an increasing concern.

DISCUSSION...A mesolow that has developed along a very slow moving
cold front draped over central Texas is tapping into 30-35 kt
southeasterly flow of Gulf moisture at 850 mb. This low and fronts
are providing ample forcing for thunderstorms that have a history
of producing 3 inch per hour rainfall rates northwest of San
Antonio. The storms are aligned parallel to the I-35 corridor. As
the storms grow upscale, they're backbuilding southwestward
towards the Rio Grande. For the very near-term there is little
pushing the front as the southeasterly flow ahead of the front is
being countered by 10-20 kt NNW flow of dry air behind the front.
Since these air flows are almost exactly antiparallel to each
other, they're supporting the mesolow that has formed west of San
Antonio. Further, they will work to keep the synoptic setup from
moving too much for the next few hours.

An approaching upper level shortwave over northwest Texas is
gradually moving east towards the storm complex. This will
increasingly work to push the complex of storms towards the east
faster, which will consequently reduce the flash flooding threat
with time. CAMs guidance is in good agreement in this scenario,
albeit with variable timing due to poor handling of the current
storms.

The storms are currently over Austin and are just about into the
San Antonio metro at the time of this writing. Expect a
multiple-hour period of heavy rain associated with the storms.
Considering the reduced FFGs associated with the urban centers,
urban flash flooding is an increasing concern over the next few
hours until the aforementioned shortwave moves the storms east of
the I-35 corridor.

Wegman

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!61EcCrLagqB-PnpGFdGXXXNvzO_9Ansvi4vY338kfBocDm8ZRg_LpXoE_OTgMGb_gFMz= nb69J93CZIYdRcgzIQtA42k$ for graphic product...

ATTN...WFO...CRP...EWX...FWD...HGX...

ATTN...RFC...WGRFC...NWC...

LAT...LON 30859753 30659687 29829679 28959744 28619830=20
28489942 28939983 29159952 29379924 29809881=20
30539813 30819789 30829787=20

=3D =3D =3D
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AWUS01 KWNH 050932
FFGMPD
ILZ000-LAZ000-MOZ000-ARZ000-TXZ000-051530-

Mesoscale Precipitation Discussion 1129
NWS Weather Prediction Center College Park MD
431 AM EST Tue Nov 05 2024

Areas affected...mid-MS Valley into central AR and the Arklatex

Concerning...Heavy rainfall...Flash flooding likely

Valid 050930Z - 051530Z

SUMMARY...Flash flooding is expected to continue from near and
south of the St. Louis metro/mid-MS Valley southwestward into the
Arklatex through 15Z. While rainfall rates will be lowering
overall, occasional pockets of higher rates will maintain areas of
flash flooding, especially atop saturated soils.

DISCUSSION...Regional radar imagery at 09Z showed an elongated
axis of showers and thunderstorms which stretched from the St.
Louis metro into south-central MO, west-central AR and the
Arklatex. This axis was located along a combined cold/stationary
front and outflow boundary which was coincident with the leading
edge of heavy rain. Trends in rainfall intensity have shown a
decrease in higher rainfall rates over the past few hours as
instability has been lowering. 09Z SPC mesoanalysis data showed
MLCAPE values were at or less than 500 J/kg just ahead of the
combo front/outflow boundary from MO into AR, but increased to
1000+ J/kg over TX. However, the southern portion of the
front/outflow was progressing steadily toward the east, to the
south of weak wave located ~40 miles southeast of FSM, limiting
the flash flood threat for these southern locations. To the north,
the front/outflow has been very slow to progress with locations
just south of I-44 in eastern MO to the St. Louis metro containing
repeating and training echoes for the past 2-3 hours.

Water vapor imagery showed the former closed mid-level low over
the southern High Plains has begun to open up and elongate from
SSW to NNE. Just ahead of the elongating upper vorticity max was a
GOES-East DMV sampled 130+ kt jet streak over eastern KS,
providing increased lift via strengthening divergence aloft over
northern AR into MO within the right-entrance region. As the mid
to upper-level trough axis continues to translate east, it is
forecast to acquire more of a neutral tilt with the downstream jet
streak allowing for an extended period of enhanced lift over MO.

Therefore, while instability will continue to gradually lower
until sunrise (~12Z), dynamic forcing will support occasional
pockets of higher rainfall rates within areas of training that
will continue to support pockets of rainfall rates of 1-2 in/hr
within an anomalous moisture axis containing PWATs up to 1.8
inches. This potential will exist from near the Arklatex to the
central and southern MO/IL border, overlapping portions of the
region which have seen heavy rainfall over the past 24 hours.
Overlap of additional rainfall with prior rainfall is expected to
be greatest across MO into northern AR, but at least an isolated
flash flood threat will continue for locations farther south into
northwestern LA and northeastern TX. Additional rainfall totals of
2-3 inches are expected through 15Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_opc69QMvdrTu-My0ZY0aWZubvA7qylLDKEG21zAWZLR3L4iI5l4BGmrDf_vkk22iL_7= DsEYgJvmZ6xBI6QMY-JS9x0$ for graphic product...

ATTN...WFO...LSX...LZK...PAH...SGF...SHV...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...WGRFC...NWC...

LAT...LON 39058971 38568953 37339024 35379164 33599272=20
32389359 31859456 31949496 32439503 33479441=20
35299351 36799266 38379143 39049063=20

=3D =3D =3D
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AWUS01 KWNH 060534
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MSZ000-LAZ000-MOZ000-ARZ000-061115-

Mesoscale Precipitation Discussion 1130
NWS Weather Prediction Center College Park MD
1234 AM EST Wed Nov 06 2024

Areas affected...AR/MS border into western TN/KY and the lower OH
Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 060532Z - 061115Z

SUMMARY...Training/repeating rounds of showers and thunderstorms
may produce a couple areas of localized flash flooding through 11Z
from the AR/MS border into western TN/KY and the lower OH Valley.
Rainfall rates up to 3 in/hr will be possible, although 1-2 in/hr
should be more common. Coverage is expected to remain localized.

DISCUSSION...Regional radar imagery showed a broken axis of
showers and thunderstorms stretching from southwestern IN into the
lower MS Valley at 05Z, along and ahead of a slow moving cold
front. 05Z data from the SPC mesoanalysis showed that MLCAPE of
500-1000 J/kg extended from the lower MS Valley into southwestern
TN with weak (<500 J/kg) MLCAPE and MUCAPE to the north into the
lower OH Valley. Slow eastward movement of the boundary and
anomalous moisture (PWATs of 1.5" along the IN/KY border,
increasing to near 2.0" along the AR/MS border) were supporting
locally high rainfall rates within areas of training. Peak
rainfall rates were observed in the 2.5 to 2.7 in/hr range in
Lauderdale County in western TN just prior to 05Z but that axis of
heavy rain has since shifted east.

Forecast movement of the boundary is for slow but steady eastward
progress northward of northern TN, but for nearly stationary
movement south of Memphis. Water vapor imagery showed a subtle
shortwave trough over western LA into the Gulf with slight
buckling of the downstream flow over the lower MS Valley which may
help to support a weak surface wave along the front in LA and
stalling of the front to its immediate north. 25-35 kt of 925-850
mb flow from the S to SSW (despite gradual weakening overnight)
may allow for the repeated regeneration of showers/thunderstorms
over the AR/MS border with areas of training toward the NNE just
ahead of the slow moving front. Rainfall rates of 1-2 in/hr
(locally higher) will be possible within axes of training
resulting in 2 to 3 inches (locally higher) through 11Z.

Farther north, the flash flood threat is expected to be more
limited due to the eastward progression of the cold front, limited
instability and the departing of right-exit region ascent tied to
a 120-140 kt over IL/IN/MI. However, an isolated flash flood
cannot be completely ruled out overnight.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5Bk5mj0ywGnmHWHTyuAFOz-KVfnWT0oULFfhLEklzQV8SadaiI_X3Phr2Nx0D5CLUonO= sXd0xVKAs8i8HSXc7fIwlI0$ for graphic product...

ATTN...WFO...JAN...LMK...LZK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON 38478748 38208676 37808664 36888701 35518831=20
34298969 33449075 32979134 33159167 34189099=20
35698987 36638920 38108796=20

=3D =3D =3D
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AWUS01 KWNH 061402
FFGMPD
MSZ000-LAZ000-061800-

Mesoscale Precipitation Discussion 1131
NWS Weather Prediction Center College Park MD
901 AM EST Wed Nov 06 2024

Areas affected...Central and Northeast LA...Southwest MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 061400Z - 061800Z

SUMMARY...Slow-moving areas of heavy showers and thunderstorms are
expected to continue through the morning hours. Some localized
areas of flash flooding will be possible, and especially given
very high rainfall rates and some cell-training concerns.

DISCUSSION...The latest GOES-E IR satellite imagery in conjunction
with dual-pol radar shows slow-moving areas of heavy showers and
thunderstorms focusing along and just ahead of a quasi-stationary
front situated from southwest LA northeastward through
west-central MS. The convection has been showing persistence and
localized expansion in coverage over the last couple of hours, and
is being influenced by proximity of a weak area of surface low
pressure along the front.

This is yielding an axis of relatively strong low-level moisture
convergence which is also embedded within a somewhat unstable
boundary layer characterized by MLCAPE values of around 1000 J/kg.
The upper-level flow over the northwest Gulf Coast region is also
seen becoming increasingly divergent and this is also facilitating
deeper layer ascent with a low-level convergent response ahead of
the aforementioned wave of low pressure.

Recent MRMS data has been showing some of the active areas of
convection over central LA producing rainfall rates of as much as
2 to 3 inches/hour and this is being aided by PWs of 1.75 to 2
inches which are about 2 standard deviations above normal for this
time of the year.

Additional rainfall amounts of up to 3 to 5 inches will be
possible by late this morning given the slow cell-motions and
occasional cell-training concerns. This is supported by the 12Z
HRRR guidance, and this may result in some localized areas of
flash flooding. The main threat will tend to be over central to
northeast LA, but some of this could potentially spread into
portions of southwest MS by later this morning.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7urNP6j1PqnxfxCgA5LmFnnJ2ZgtdLDh7bxmZtw7cVdlJA4xD0Xz2Puk9yUH3YzwW5o6= ClXO94nn4iWBtE11iYuxT_w$ for graphic product...

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...NWC...

LAT...LON 32769106 32379083 30989151 30219222 30239287=20
30889267 32119195=20

=3D =3D =3D
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AWUS01 KWNH 061931
FFGMPD
SCZ000-GAZ000-ALZ000-070130-

Mesoscale Precipitation Discussion 1132
NWS Weather Prediction Center College Park MD
230 PM EST Wed Nov 06 2024

Areas affected...Central and Eastern GA...SC Midlands and
Lowcountry

Concerning...Heavy rainfall...Flash flooding possible

Valid 061930Z - 070130Z

SUMMARY...Increasing coverage of showers and thunderstorms is
expected going through the evening hours. Very heavy rainfall
rates and localized areas of cell-training will result in a
gradually increasing flash flood threat, and especially for the
more urbanized locations.

DISCUSSION...Deep layer tropical moisture transport extending well
north of Hurricane Rafael is seen in CIRA-ALPW imagery advancing
northwestward into the Southeast U.S. Already the PWs across much
of southern GA have increased to 2.25+ inches, and some additional
increase in the PWs will be expected this evening as deep layer
southeast flow persists over the region.

Meanwhile, this will couple with increasing boundary layer
instability in vicinity of a surface trough and developing
right-entrance region upper-level jet dynamics for broken areas of
very heavy shower and thunderstorm activity. MLCAPE values are
already locally on the order of 1000 to 1500 J/kg, and satellite
imagery is showing an increasingly divergent flow pattern aloft
associated with favorable placement of the upper-level jet near
the Southeast U.S.

Radar and satellite imagery are showing rather rapidly expanding
areas of convection with cooling cloud tops across central and
eastern GA, and some additional increase in coverage is expected
going through the evening hours as deep layer forcing/ascent
increases further which will likely include portions of the SC
Midlands and Lowcountry.

Some of the convection is expected to become locally very
concentrated heading into the evening hours, with some potential
for alignment of the activity in a cell-training manner. The 12Z
HREF guidance and recent runs of the HRRR have been supporting
this and suggest some impressive rainfall totals this evening,
with additional heavy rainfall totals extending well into the
overnight period.

Given the deeply tropical environment, the rainfall rates will be
extremely efficient with 2 to 3+ inch/hour rates eventually
becoming likely. The cell-training concerns associated with this
will favor some storm totals by mid-evening to reach as high as 3
to 6 inches.

Initially with the very dry antecedent conditions, the flash flood
threat will tend to be a bit conditional, and will tend to be more
of a concern for the more sensitive urbanized areas. However, the
flash flood threat is expected to increase further overnight as
additional heavy rains develop and persist over the same area.
Additional MPDs will be issued accordingly.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5rF2haKG-qNTL-6Kg23eop2qrA7ZRId4zdFWFIBe9K1ugPsaom58G_0KTODq7h_81ams= x5YvuK9vHDq8YnNvPgPAQ6w$ for graphic product...

ATTN...WFO...BMX...CAE...CHS...FFC...JAX...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON 33918253 33868101 33028086 31778180 31408339=20
31838466 32328510 32948489 33588379=20

=3D =3D =3D
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AWUS01 KWNH 062317
FFGMPD
SCZ000-FLZ000-GAZ000-070515-

Mesoscale Precipitation Discussion 1133
NWS Weather Prediction Center College Park MD
615 PM EST Wed Nov 06 2024

Areas affected...Portions of the FL Panhandle...Southern and
Eastern GA...SC Midlands and Lowcountry

Concerning...Heavy rainfall...Flash flooding likely

Valid 062315Z - 070515Z

SUMMARY...Heavy showers and thunderstorms will continue to
generally increase in coverage and concentration heading into the
overnight hours. There will be concerns for extreme rainfall rates
and some cell-training which is expected to result in scattered to
numerous areas of flash flooding. Some of this may become
particularly significant and life-threatening.

DISCUSSION...Deep layer tropical moisture transport continues into
the Southeast U.S. well to the north of Hurricane Rafael which is
currently crossing western Cuba. The latest CIRA-ALPW imagery
shows strong concentrations of this tropical moisture in the low
and mid-levels of the vertical column, and overall the PWs now up
across the FL Panhandle into central and southern GA have risen
into the 2.25 to 2.5 inch range based on some of the polar
microwave and GPS data.

This moisture transport continues to work in tandem with MLCAPE
values of as much as 1000 to 1500 J/kg and proximity of a surface
trough to promote numerous areas of heavy showers and
thunderstorms. Radar generally shows the greatest concentrations
of convection focused over areas of southern and eastern GA and
into portions of the central SC. The flow aloft continues to be
increasingly divergent which is showing up well in the GOES-E IR
satellite imagery along with the expansion of cooling convective
tops as favorable upper-level jet divergence sets up.

The latest 18Z HREF guidance and HRRR solutions support locally
some additional expansion of convection along with a likelihood
for this activity to become increasingly concentrated and focused
over areas of east-central GA and potentially edging into parts of
the SC Midlands and Lowcountry heading into the overnight hours.

The deeply tropical environment coupled with the level of
instability and low to mid-level shear may favor some particularly
high rainfall rates overnight. Some of these rates may reach 2 to
4 inches/hour and will tend to be maximized with any mesocyclone
activity that occurs near the aforementioned surface trough axis.
The cell-training concerns associated with these rates will favor
additional rainfall totals of 4 to 6 inches by midnight with
locally heavier amounts possible.

Dry antecedent conditions at least in the short-term will continue
to locally mitigate the flash flood threat, but as these extreme
rainfall rates materialize and persist into the overnight hours,
there will eventually be scattered to numerous areas of flash
flooding, and some of this may become significant and
life-threatening.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6RoZcw210YMUGotFsTAKGFrD0NmdNnBMQ1igOKYCIYatvrAKjY92RtY2oILmuvkyqikM= JEjmKTml0zvg7GUJhF7jNGA$ for graphic product...

ATTN...WFO...CAE...CHS...FFC...GSP...JAX...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON 34288093 33748053 32918090 32158149 31268222=20
30418339 30288427 30828487 31858463 32988367=20
34238202=20

=3D =3D =3D
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AWUS01 KWNH 070454
FFGMPD
SCZ000-FLZ000-GAZ000-071100-

Mesoscale Precipitation Discussion 1134
NWS Weather Prediction Center College Park MD
1154 PM EST Wed Nov 06 2024

Areas affected...Southeast GA...Eastern SC...Eastern FL
Panhandle...

Concerning...Heavy rainfall...Flash flooding likely

Valid 070500Z - 071100Z

SUMMARY...Flash flooding likely to continue with slow
moving/stationary PRE-like precipitation shield. Embedded
convective cells with 2-2.5"/hr may result in 5-8" totals thru 12z
resulting in significant flash flooding.

DISCUSSION...Regional RADAR mosaic depicts a broad mesoscale
complex across stretching from the central GA/FL state line
through southeast GA into the coastal plain of SC. Frontal-like
features are starting to be more well defined, with surface 04z
surface analysis suggesting a weak low near VDI as well as a
meso-low responding to very strong convective complex near VLD. A
surface trof/effective developing front extends northeast through
the pressure trof to about DYB/CHS providing a favorable boundary
for further ascent.=20

RAP analysis continues to denote a very strong divergence
signature at the right entrance of a passing polar jet across the
Carolinas along with modest diffluent pattern over SE GA/N FL as
contribution from anticyclonically curved outflow jet from
periphery of approaching Tropical Cyclone Rafael. This
divergence signal is slowly lifting north east, but its
contribution to the development of the sfc to low level wave and
encouragement of strengthening southeasterly confluent return
moisture flow off the Gulf stream, is providing deep moisture flux
convergence and isentropic ascent across the aforementioned
boundary. CIRA LPW shows a marked increase in moisture generally
parallel to the FL coast with 1.15" Sfc to 850mb moisture advected
northeast on 25-30kts orthogonal to the boundary and as far
northwest into GA toward Macon, GA. CIRA LPW also notes that
solid core of 700-300mb moisture resides across the northeast Gulf
through South Carolina resulting in total values over 2-2.25".=20
While the profile is solidly saturated, there is sufficient low
level heating to support weak to modestly unstable air with
750-1250 J/kg of MLCAPE remaining along and southeast of the
boundary, so embedded convective elements will remain likely
through the overnight period...likely with SE to NE 'finger-like'
filaments as the overall onshore flow is strong to support about
5kts of southeast propagation.

This will allow for a broad complex of moderate showers to remain
across SE GA into SC where heavy rainfall has already resulted in
flash flooding conditions additional 2-4" totals on .5-1"/hr rates
can be expected. However, it is those embedded convective
elements with back-building that are of greatest concern. Overall
trends would suggest band of confluence showers/TCus off the Gulf
stream lifting north into SW SC will likely result in the greatest
potential totals, nearly all 00z Hi-Res CAMs support a localized
maxima in the vicinity from Bulloch to Colleton counties (HREF
neighborhood probability of 5"/6hr over 50%), providing solid
confidence there.

However, a secondary area of concern along the southern-most
flanking line of the effective boundary in south-central GA
remains a bit less certain...but already been very prolific near
Valdosta, GA. With an exiting shortwave/right entrance region,
there remains some veering of low level flow to maximize sfc to
boundary layer moisture flux convergence in proximity to the
greatest remaining instability pocket across the eastern portion
of the FL panhandle across southern GA. Isallobaric response will
likely remain the driver of this flux convergence and risk for
2-3"/hr rates. Deeper layer flow suggests this area of
convergence will drift north and westward toward an area of
lowered FFG values from prior heavy rainfall recently. As such,
while confidence that this area will be able to maintain relative
to areas northward, the risk for more isolated but heavier
rainfall rates and excessive totals remains.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4QsiGC3P41EoUF092UQbYMadJ1b-Rn0SDXhUK7WFfXdGOHCXlWbPqjrOrkAdh1t8Uru8= qLQyBbT48o6r3EM9gbuI7rw$ for graphic product...

ATTN...WFO...CAE...CHS...FFC...ILM...JAX...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON 34418013 33867906 33207910 32527986 31658092=20
31008134 31078194 31048223 30238340 30218414=20
30898440 32148370 33078284 34108136=20

=3D =3D =3D
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AWUS01 KWNH 071008
FFGMPD
SCZ000-GAZ000-071530-

Mesoscale Precipitation Discussion 1135
NWS Weather Prediction Center College Park MD
508 AM EST Thu Nov 07 2024

Areas affected...Southeast GA...Southern SC...

Concerning...Heavy rainfall...Flash flooding likely

Valid 071010Z - 071530Z

SUMMARY...Flooding likely to continue though potential for intense
rain-rates capable of inducing flash flooding reducing with time
and overall coverage.

DISCUSSION...A large area of 4-10" rainfall extends across eastern
GA into southwest to south-central SC with slow expansion toward
the coastal Plain over the past few hours. Large scale ascent
pattern remains fairly strong with upper-level divergence pattern
along right entrance of broad polar jet across the Carolinas.=20
However, the area is shifting east-northeast and reducing
slightly. Still, this is maintaining a solid dual fetch of
low-level flow from the northeast Gulf as well as off the Gulf
stream parallel to the NE FL/GA coast. Cold pool from the heavy
rainfall continues to allow for a moderately steep isentropic
boundary across the area from SE GA into the Low Country, with a
very slow east-southeast drift due to the responding low level
inflow from the south-southeast. VWP denotes continued 20-25kts
of SE flow nearly orthogonally intersecting the boundary and
northeasterly flow across central SC. CIRA LPW and RAP analysis
denote deep profile of highly anomalous moisture with values of
2.25" through depth with sfc-850mb over from .9" to 1.15" across
the area of concern; so dynamics and moisture continue to be in
place to maintain rainfall efficiency.=20

However, unstable air mass continues to diminish in areal coverage
and intensity as the profile becomes more staturated and warms
aloft; restricting itself to the Gulf Stream and coastal GA where
low level flow has been generally divergent before starting to
accelerate into SE SC where convergence is maximized. Values of
500-1000 J/kg remain but only along the upstream edge of the
complex along the Savannah River Valley. As such, limited
overall convection capable of rates over 1.5-2"/hr are expected
over the diurnal minimum in activity of early morning/daybreak,
mainly near/southeast of mid-level exiting shortwave seen near
Wilkenson county, GA or at the 700-850mb low feature seen in RADAR
in Montgomery county. Smaller localized spots of 2-4" totals
remain possible to induce new incidents of flash flooding though
the 15z period.

Moderate downstream blow-off shield precipitation within the more
gentle isentropic ascent pattern will maintain moderate rainfall
rates across the flooded areas from Emanuel to Orangeburg with
counties with occasional hourly rates exceeding .5". This will
likely help to maintain the expanding riverine flooding as pluvial
flooding continues to channel into localized creeks/streams. An
additional 2-3" remains possible through the morning hours given
favorable upstream redevelopment and training as the upper-level
forcing moves northeast.

As such, flooding will remain likely across the area of concern,
though incidents of flash flooding are considered possible given
reducing coverage/intensity required to exceed FFG where heavier
rain did not fall last evening/overnight across coastal E GA/S Low
Country of SC.=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7KrKv4WH9irWGj-XPJJQSsd03infN2eK6yLMWHxkshwpLkQNiGmy677k2jkIUv-D8ixG= 2-gtf15TA2-jcdygL8CFC7A$ for graphic product...

ATTN...WFO...CAE...CHS...FFC...ILM...

ATTN...RFC...SERFC...NWC...

LAT...LON 34118019 33907956 33397924 32977945 32757980=20
32578007 32208058 31698098 31418123 31528156=20
31888193 32048228 31938282 32008307 32298309=20
32688271 33158214 33478172 33678137 34038071=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 071535
FFGMPD
SCZ000-GAZ000-071930-

Mesoscale Precipitation Discussion 1136
NWS Weather Prediction Center College Park MD
1035 AM EST Thu Nov 07 2024

Areas affected...Southeast GA into Far Southern South Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 071534Z - 071930Z

SUMMARY...Additional flooding is possible into the afternoon over
parts of southeast Georgia into far southern South Carolina
although the potential for intense rain-rates capable of inducing
flash flooding should diminish with time.

DISCUSSION...On-going convection capable of producing isolated
areas of an additional 2 to 4 inches of rain will perisit over
portions of southeast Georgia into far southern South Carolina
with isolated spots receiving rainfall rates approaching 1.5 inche
per hour. Large scale ascent pattern remains fairly strong with
upper-level divergence pattern along right entrance of broad polar
jet across the Carolinas. However, the area of heaviest rainfall
rates has shifted south and east of the area hardest hit overnight
and should continue to shift closer to the coast into th
afternoon. Still, this is maintaining a solid dual fetch of
low-level flow from the northeast Gulf as well as off the Gulf
stream parallel to the NE FL/GA coast. Cold pool from the heavy
rainfall continues to allow for a moderately steep isentropic
boundary across the area from SE GA into the Low Country, with a
very slow east-southeast drift due to the responding low level
inflow from the south-southeast. CIRA LPW...RAP analysis and 12Z
soundings denote deep profile of highly anomalous moisture with
values of 2.25" through depth with sfc-850mb over from .9" to
1.15" across the area of concern; so dynamics and moisture
continue to be in place to maintain rainfall efficiency.=20

However, instability should linger in an increasingly small areal
coverage which should help limit overall convection capable of
rates over 1.5 inches per hour and localized 2-4" totals remain
possible to induce new incidents of flash flooding although any
additional rainfall ovee areas soaked overnight will likely result
in continued (if not worsening) ongoing flooding.=20

Bann

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4vPr74HAmWnkcsSQ-9qcLHtsd97mnbkX8MuR_mRwriti8-Q8JPBVnk2AcJnjSvWpsBY_= u6zsupGjeo0N-JNjpId4VRY$ for graphic product...

ATTN...WFO...CHS...FFC...JAX...TAE...

ATTN...RFC...SERFC...NWC...

LAT...LON 32658107 32618067 32468052 32228064 31618117=20
31288148 31078197 30908246 30988303 31178311=20
32088219=20

=3D =3D =3D
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AWUS01 KWNH 072105
FFGMPD
TXZ000-OKZ000-080300-

Mesoscale Precipitation Discussion 1137
NWS Weather Prediction Center College Park MD
404 PM EST Thu Nov 07 2024

Areas affected...Parts of North Texas to Southwest Oklahoma

Concerning...Heavy rainfall...Flash flooding possible

Valid 072103Z - 080300Z

SUMMARY...Showers and thunderstorms capable of producing heavy
rainfall that results in areas of excessive rainfall will become
more numerous during the afternoon and evening.

DISCUSSION...An increase in the coverage of showers and
thunderstorms is expected to continue this afternoon and evening
in a region of low level convergent flow while the flow aloft
becomes increasingly difluent/divergent. With the low level flow
tapping an airmass with precipitable water values at or above 1.5
inches gets drawn towards the region of low level
convergence...any convection in the area should become
increasingly efficient rainfall producers.

Moisture transport will be working in tandem with MLCAPE
values approaching 1000 J/kg and the approach of a low level
surface warm front later in the afternoon as shown by the 12Z HREF
and latest HRRR runs...helping to provide a focus for the
organized convection.

The expectation is that risk of excessive rainfall will initially
be widely scattered and tied more to rainfall rates.=20
However...the synoptic scale forcing of upper level divergence
combined with the mid and low level mesoscale forcing suggests
that the risk of excessive rainfall will continue to grow in
coverage for the remainder of the afternoon and into the evening.

Bann

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9LO1tGJzq498dPI3ufT-sKRcmiHD91MR6OKGTMXeqC4ZCEQtdmcqSX_fO20Vo4lhExeh= rOO_1_B7vPIC5YvXLJSgusM$ for graphic product...

ATTN...WFO...AMA...FWD...LUB...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 36330047 35389891 34019734 32729703 32139698=20
31519752 31889892 32489972 33080014 33500051=20
34260098 35340122=20

=3D =3D =3D
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AWUS01 KWNH 080255
FFGMPD
TXZ000-OKZ000-080830-

Mesoscale Precipitation Discussion 1138
NWS Weather Prediction Center College Park MD
954 PM EST Thu Nov 07 2024

Areas affected...Lower Pecos/Concho Valleys into Northwest Texas
Big Country...

Concerning...Heavy rainfall...Flash flooding likely

Valid 080300Z - 080830Z

SUMMARY...Slow moving/training thunderstorms with 1.75-2"/hr rates
pose line of 2-4" totals with possible embedded 5+" resulting in
likely incidents of flash flooding through the overnight period.=20

DISCUSSION...GOES-E WV suite continues to show anomalously deep
closed low over northern NM with broad southwesterly flow aloft
crossing the Southern High Plains. While the upper-low is filling
slowly, there are two main vorticity centers with the northern
swinging around the NE side of the circulation int SE CO, while
the base energy is starting to advance out of AZ. This continues
to support a very strong and diffluent jet across much of western
Texas providing a broad area of vertical ascent. Near the
surface, the low level jet has been responding throughout the
evening with solid 30 kt south-easterly flow. Initial surge of
enhanced moisture has already intersected the deeper NNE to SSW
convergence axis from NW TX toward the Lower Pecos River Valley
and has brought total PWat values into the 1.5" range in proximity
to the western edge of the instability gradient and has supported
expanding clusters of thunderstorms with a few rotating updrafts
within a cluster or two across E OK into the northern Concho
Valley, with a few more individual cells further south. CIRA LPW,
notes that a secondary surge especially in the surface to 850mb
layer is starting to reach the Lower Pecos and into Concho Valley
with .6 to .75" values at the nose of the 30kts, this will
continue through the early overnight period and eventually expand
along the length of the convergence axis (area of concern). This
will increase convective coverage as well as moisture flux into
the cells. Modest instability (1000+ J/kg) will be aided by the
divergence aloft to maintain stronger updrafts and result in
expanding downdrafts capable of 1.5-2"/hr.

Greater concern is going to be residency of this
ascent/convergence axis to allow for additional development
(particularly upstream in SW TX where a weak 850mb low will be
forming and lifting northward through the evening with the
approaching height-falls/dPVA. As the base shortwave swings
east, overall orientation of the flow will back more southerly and
allow for deeper steering flow to align more with the generally
stationary convergence axis. Cells further south near the
surface low (between) SJT/BRD and frontal zone, cells may have
increased depth of moisture flux...before becoming more elevated
across Nw Texas. As such, training may result in a band of
excessive rainfall totals of 3-4" with embedded spots over 5" not
out of the realm of possibility. While areas of the Concho/Pecos
Valley have higher FFG values, there remains solid likelihood of
exceeding resulting in flash flooding conditions tonight. Lower
FFG values from Nolan/Callahan and points north increase the
potential for exceedance (<2"/hr & 2-2.5" in 3hrs). As such,
flash flooding is considered likely and with above normal
confidence given the overlapped weather elements and fairly solid
agreement in the Hi-Res CAM suite.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_A2Fs_mgfufkPhueckyGmQJMM-xfyGJa9SDVNnaa2sv3cw8XYm9uKUIKn8iQ-IT8C-lh= Cb1D2MKfy89NKxFZuq-bWPQ$ for graphic product...

ATTN...WFO...EWX...FWD...LUB...MAF...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 34389920 34239832 33599779 32579782 31509872=20
30699954 30140012 29650110 29940199 30700183=20
31550137 32950059 33940019=20

=3D =3D =3D
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AWUS01 KWNH 080321
FFGMPD
TXZ000-OKZ000-080900-

Mesoscale Precipitation Discussion 1139
NWS Weather Prediction Center College Park MD
1020 PM EST Thu Nov 07 2024

Areas affected...Western Oklahoma...Eastern Texas Panhandle...

Concerning...Heavy rainfall...Flash flooding possible

Valid 080320Z - 080900Z

SUMMARY...Scattered clusters of elevated thunderstorms with
1-1.5"/hr rates and possible training/repeating may result in a
scattered incident or two of localized flash flooding given lower
FFG values in the area.=20

DISCUSSION...GOES-E WV suite depicts an anomalously strong (2-3
standard anomaly) closed low across S CO/N NM with lead vorticity
center starting to retrograde over the top of the parent center of
the closed low. This is resulting in downstream backing of deeper
layer flow, particularly in the 850-700mb layer providing
sufficient moisture flux and weakly steeper lapse rates for some
weak MUCAPE (about 500 J/kg or less) in proximity of the Red
River. Solid/consistent convergence along the TROWAL axis that is
generally along 100W along with this instability has sprouted and
helped to maintain redevelopment of convective clusters across far
NW Texas into SW OK. Solid moisture flux values on 30-35kts
850-700mb veering flow and CIRA LPW values at .33-.5" through the
layer (and totals of 1.25") has supported modest rainfall
production with these elevated cells. Spots of 1-1.5"/hr rates
have been seen and current trends along the TX/OK border suggest
similar rates may be expected over the coming hours.=20

As the vorticity center continues to retrograde, deeper southerly
influence and stronger moisture flux from the south (see MPD 1138
for additional upstream development) should help to maintain
scattered potential for training/repeating elements through the
early overnight period and as such, spots of 1.5-3" are possible.
Ground conditions have been wetter than most areas across the
Plains recently, with slightly above average deep soil moisture
and so FFG values are slightly lower and within range of these
hourly and 3hrly totals. As such, a spot or two of flash flooding
is considered possible.=20=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_2bhqxm_lXbf9rpwq-COCY8Dmg6MW0FYTV7OcZbasXcrpQD2RypU7YhE6RieIjP7RpqB= _A6pc3kU70py0BFq0RqNNgk$ for graphic product...

ATTN...WFO...AMA...LUB...OUN...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 36979834 36889762 36069744 34949802 34369893=20
33789999 33540105 34170178 35290116 36010043=20
36719966 36959913=20

=3D =3D =3D
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AWUS01 KWNH 080807
FFGMPD
TXZ000-OKZ000-081330-

Mesoscale Precipitation Discussion 1140
NWS Weather Prediction Center College Park MD
306 AM EST Fri Nov 08 2024

Areas affected...Central to North TX...far South-central OK...

Concerning...Heavy rainfall...Flash flooding possible

Valid 080815Z - 081330Z

SUMMARY...Flash flooding threat continues with slow moving
thunderstorms but with reducing instability coverage and intensity
should be reducing through 12z.

DISCUSSION...GOES-E WV suite shows large scale upper-level closed
low has moved to a more neutral orientation on its way toward a
weak negative tilt over eastern NM. VWP and RAP analysis suggest
surface to 850 cyclogenesis is starting to break off into a closed
low across the Lower Pecos moving into the Concho Valley. GOES-E
3.9um SWIR and RADAR mosaic note the backed/slowing low level flow
near the splitting point out of the Rio Grande Valley has resulted
in the southern most cell starting to lift with the forcing wave
as it lifts north. Still, along and downstream of the low within
the weak split jet flow aloft/along the best divergence axis
aloft, a classic-wedge EIR pattern has formed though is starting
to broaden and round with weakening overall flow and slow
breakdown of the best ascent. Still, VWP 850-700mb flow remains
solid for the next few hours with deep moisture flux convergence
maximized with said axis from Runnels to Stephens to Jack counties
in Northwest Texas. Total Pwats over 1.75" and modest but still
supportive 500-1000 J/kg CAPE will maintain the potential for
1.5-2"/hr rates for the next 3-4 hours, slowly waning with time.=20

Deep layer steering will continue to allow for convective elements
to align and train/repeat and will support 2-4" totals with higher
values north and east of the surface wave. However, the overall coverage/breadth of the downdrafts may reduce the overall coverage
of the 3-4" in favor of a broader area of 2-3" as the best upper
level support reaches the Red River Valley into south-central OK.=20
As such, while flash flooding is likely to continue where the
swath of 3-6" from Runnels to Palo Pinto county as the last cells
in the train move through; the probability of new incidents of
flash flooding northward will become more isolated with time and
so the risk reaches the possible flash flooding assignment
category versus likely...though potential increases with any
crossing of urban or traditionally prone localized areas across
Northwest and Northern Texas through 14z.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_K2yMoRbyrD22CT08Q6RGYnR85OHUV3sDkBUD-o_ZSXcX8iezfT9veSwlOmPPvMxFR57= -YzNe003ipu4xGfR-ub83DQ$ for graphic product...

ATTN...WFO...FWD...OUN...SJT...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 34959734 34579682 34459669 33909670 32879731=20
31729856 31209951 31390018 32080010 33199956=20
34729835=20

=3D =3D =3D
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AWUS01 KWNH 082226
FFGMPD
LAZ000-TXZ000-090425-

Mesoscale Precipitation Discussion 1141
NWS Weather Prediction Center College Park MD
525 PM EST Fri Nov 08 2024

Areas affected...much of northern and eastern TX...adjacenet
portions of northwestern LA

Concerning...Heavy rainfall...Flash flooding possible

Valid 082225Z - 090425Z

Summary...1-2"/hr rainfall rates may result in 2-4" localized
totals, isolated to widely scattered instances of flash flooding.

Discussion...Convective coverage and intensity is increasing
across a narrow (but clearly defined) warm sector late this
afternoon, encompassing much of northern and eastern TX. The
mesoscale environment is characterized by ML CAPE of 500-1500
J/kg, PWATs of 1.6-1.8 inches (above the 90th percentile, per
FWD/SHV sounding climatology), and effective bulk shear of 30-40
kts. While forcing is rather limited (with DPVA and jet dynamics
displaced to the northwest with the occluded low), there is
sufficient moisture, instability, and shear to result in loosely
organized convection. The stronger cells are capable of localized
rainfall rates of 1-2"/hr, which may locally repeat to result in
some 2-4" totals. With antecedent conditions being relatively dry
(as 3-hr FFGs generally ranging from 2-4"), isolated to widely
scattered instances of flash flooding are considered possible.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_qFjaY6-bGcjlRihJsvbuldex8RDL9fI5kXEfqniJxyGoDHDQdZZ_kEJ1WTR9IfM3yDb= Yv_a0oFQh492S_v5ufP3-Go$ for graphic product...

ATTN...WFO...EWX...FWD...HGX...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 33479740 33369634 32969547 32679460 32449374=20
31739351 30469417 30149512 30139626 30359702=20
31259743 32129762 32899763=20

=3D =3D =3D
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AWUS01 KWNH 090354
FFGMPD
LAZ000-ARZ000-TXZ000-090900-

Mesoscale Precipitation Discussion 1142
NWS Weather Prediction Center College Park MD
1054 PM EST Fri Nov 08 2024

Areas affected...Eastern TX...Adj. Northwest/Western LA...

Concerning...Heavy rainfall...Flash flooding possible

Valid 090400Z - 090900Z

SUMMARY...Potential for intense but scattered clusters of cells
with efficient rainfall production possibily resulting in
localized flash flooding.=20

DISCUSSION...03z surface analysis depicts a triple-point low near
FF4 and TYR at eastern-most bulge in the progressive cold front
across N Texas through to the Central Texas Coastal Plain. An
ill-defined stationary front extends generally due east and
demarcates sfc Tds in the high upper 60s/low 70s from lower values
northward in NE TX. The upper-low pressing eastward and
associated height-falls are diminishing with its filling and so
low level response in wind flow has seen a marked decrease to
20-25kts across the warm sector becoming more parallel to the cold
front. Generally reducing flux and overall moisture convergence to
maintain a broader area of ascent. However, this is resulting
into increased orthogonal intersection with the the stationary
front providing isentropic ascent/convergence where moisture
remains most pooled. Total PWat values remain AoA 2", and while
there is a weak connection to low level moisture from outer
periphery of Rafael's moisture pool, the winds are generally below
15kts and so not really connecting to increase, but more weakly
maintain the moisture across the warm sector.

Unstable air in the warm sector still is more than sufficient to
promote stronger updrafts, but given the weakening flow cells may
become a bit more clustered/isolated. MLCAPEs of 500-1000 J/kg,
2" PWs and 20-25kts should still support downdrafts capable of
1.75-2"/hr. The limiting factor is likely to be residency,
probability of totals over 2.5-3" are likely to be limited to the
strongest cores. Though there is some potential that expanding
eastward development along the isentropic boundary into LA may
allow for some repeating convection with slow eastward cell
motions along the slowing front. As such, a widely scattered
incident or two of 3-4" is not out of the realm of possibility and
have the potential to result in localized flash flooding concerns
with best chances along/downstream of the triple point and
stationary front.=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7-jK2R8d8jFPIAVX4plhszCimB7X3SQBM7bAJKjsHGzftCGy6YPdq9AArZUqiUBjXN4A= XOBTOHsi6DD3THFAgchYqHY$ for graphic product...

ATTN...WFO...FWD...HGX...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 33329498 33259398 32849342 32319323 31709335=20
31069371 30549439 30479540 30959577 31799570=20
33049567=20

=3D =3D =3D
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AWUS01 KWNH 090725
FFGMPD
LAZ000-TXZ000-091200-

Mesoscale Precipitation Discussion 1143
NWS Weather Prediction Center College Park MD
225 AM EST Sat Nov 09 2024

Areas affected...Far Southeast TX...Southwest LA...

Concerning...Heavy rainfall...Flash flooding possible

Valid 090725Z - 091200Z

SUMMARY...Persistent redeveloping warm cloud tropical showers
likely to proliferate over the next few hours with localized
totals over 4" possible. Flash flooding is becoming increasingly
possible through early morning.

DISCUSSION...GOES-E 10.3um and LCH RADAR loop shows a few shallow
topped cells across Hardin/Jefferson county that are starting to
expand in coverage along a boundary layer convergence axis from
Galveston Bay north-northeastward eastward of the approaching cold
front. VWP and RAP analysis 850mb analysis shows 15-20kts of ESE
flow slowing and stretch both northward toward the exiting
northern stream shortwave associated with diffluent portion of the
cyclonically curved 3H jet streak over E TX, and peripheral
influence approaching tropical cyclone Rafael. This is resulting
in solid speed convergence at the nose/pool of enhanced surface to
850mb moisture (which further totals to near 2-2.2"). Proximity
to the warmer theta-E off the Gulf, convective development has
been fueled by sufficient 1500-2000 J/kg SBCAPE. While the overall
depth of the updrafts are not very deep, the overall moisture flux
convergence is sufficient for 2"/hr rates.=20

Localized storm effects and approach of the cold front also have
been aiding some flanking line development to counteract the slow north-northeast cell motions and allowing for increased rainfall
totals over the last few hours in Hardin county. While much of
the Hi-Res CAM suite has been deficient of development, the
placement in those hi-res CAM fields seem to be displaced west and
reduced in overall deeper layer convergence. One solution that
appears to have this stronger convective axis is the FV3 CAM,
which does suggest an narrower overall distance in the low level
convergence coverage. Confidence is not very high given the lack
of guidance support but observational trends. As such, flash
flooding is considered possible, intense, but localized.=20=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9Z4k6xfze70Dcd_-n1561acaO5OLboDz9elAXcLpq93-9bNwOaWMmyF8gbLAjhWPv0gQ= Dz6IHVAeM1_RtGSKySad9-4$ for graphic product...

ATTN...WFO...HGX...LCH...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 31039431 31039338 30609305 29929324 29599390=20
29449446 29179529 29929534 30729490=20

=3D =3D =3D
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AWUS01 KWNH 091105
FFGMPD
LAZ000-TXZ000-091600-

Mesoscale Precipitation Discussion 1144
NWS Weather Prediction Center College Park MD
605 AM EST Sat Nov 09 2024

Areas affected...Southeast TX...Western LA...

Concerning...Heavy rainfall...Flash flooding possible

Valid 091100Z - 091600Z

SUMMARY...Slow moving, highly efficient cells along the front will
continue to produce pockets of heavy rainfall and totals capable
of inducing localized flash flooding. Scattered totals over 3-5"
remain possible.

DISCUSSION...Deep layer convergence through the warm sector over
the northern Gulf and southern LA continues to drive convective
development along the slowing/approaching cold fronta across SE
TX. Strong upper-level divergence at the inflection of the
cyclonically curved jet with maximized diffluence aloft as further enhanced/expanded convective development and isentropic ascent
along and east of the triple point northeast of JAS, TX. CIRA LPW
shows enanced surface to 700mb moisture through the warm sector
though stronger 700-500 moisture along the northern coreo of
Rafael remains distant enough for stronger WAA ascent later today.
So with some weak steepening of lapse rates, modest instability
remains in proximity of the Sabine River Valley to the triple
point and should help to maintain updraft strength and focus
moisture flux convergence to support 2-2.5"/hr rates. Duration of
heavy rainfall may be more limited further north towad the
entrance of the jet/divergence maxima as it slides away with the
speed max with time. Spots of 2-4" across west-central to
north-central LA may result in possible flash flooding over the
next few hours.

Furhter south, the east-southeast surface to 850mb flow
decelerates into a col/weak surface wave near BPT. As such,
similar deep layer moisture convergence and slightly enahnced
surface based CAPE of ~1500 J/kg (due to proximity to the warmer
Gulf) is providings stronger updraft strength. Due to proximity
of slower low to midlevel flow, cells have been a bit more
stationary/slow moving with time and some suggestion of upstream
redevelopment toward the south may allow for some repeating;
duration may continue to result in very localized but intense
rainfall up to 2.5"/hr and localized totals of 3-5" over the next
few hours. Given higher natural FFG values (only locally reduced
due to 5-8" totals over Hardin, E Liberty and NW Jefferson
counties), flash flooding from similar cells may continue risk for
flash flooding.=20=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6y0ja-kMndB2N4alvpKCt4jkeWcz9qOm2DoHAuXzp-dONTaKfsOdPZF0XD7kXCwRTV7E= mvWcBA-dyczh4TMf8fSPNi8$ for graphic product...

ATTN...WFO...HGX...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32749283 32599214 32029213 31029271 29919333=20
29709366 29439446 29149487 28989532 29809504=20
30979455 32399364=20

=3D =3D =3D
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AWUS01 KWNH 091614
FFGMPD
LAZ000-TXZ000-092200-

Mesoscale Precipitation Discussion 1145
NWS Weather Prediction Center College Park MD
1112 AM EST Sat Nov 09 2024

Areas affected...southwestern and central LA and surrounding
portions of Upper TX Coast

Concerning...Heavy rainfall...Flash flooding likely

Valid 091600Z - 092200Z

Summary...Deep tropical moisture will support very high rainfall
rates of 2-3"/hr with 6-hr totals of 3-6"+. Isolated to scattered
instances of flash flooding are likely (and may locally be
significant).

Discussion...A stalling cold front is combining with deep layer
tropical moisture transport from the southeast (in association
with Tropical Storm Rafael) to result in significant moisture flux
convergence into western LA and surrounding portions of the Upper
TX coast. Precipitable water levels are indicated to be as high as
2.2 inches (per CIRA advected layered precipitable water analysis
and RAP mesoanalysis), which is well above the 90th percentile
(per experimental ALPW sfc-850mb and 850-700mb percentiles and LCH
sounding climatology) and more typical of late August to early
September. Although instability is somewhat limited (500-1000 J/kg
of ML CAPE), it remains sufficient for convection and is unlikely
to be eroded with steady low to mid level moisture transport
coinciding with peak diurnal heating. Likewise, deep layer shear
of 20-30 kts will be supportive of organizing updrafts, while
10-15 kts of deep layer flow will keep storm motions near a crawl
(particularly so closer to the coast). All in all, a concerning
mesoscale setup that will be supportive of locally significant
flash flooding.

Updated CAM guidance (12z HREF suite) is increasingly supportive
of significant rainfall totals over the next 6 hours (HREF 40-km
neighborhood probabilities for 5" exceedance, near the 10-yr ARI,
threshold being near 15%), suggesting the potential for localized
amounts of 3-6" (with rainfall rates of 2-3" due to the deep
tropical moisture and slow storm motions). With much of this same
area already having received 3-6" over the prior 6 hours (mainly
areas west of Alexandria, as well as near Winnie, TX), the
associated 4.0" 6-hr FFGs are likely underrepresentative of the
flash flood threat. Given these antecedent conditons AND the
possibility for rainfall amounts to overperform (given the ARW2
solution of localized 6"+ totals), isolated to scattered instances
of flash flooding are considered likely, and locally this flash
flooding may be significant. The threat for significant flash
flooding is also to likely extend beyond the next 6 hours, so a
subsequent MPD is expected (with the threat likely becoming even
more significant later this evening).

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_9GOqR31doEVg5fnc5xBLOKROmNKwmylL07Vg5HTjGA4LzWucYoszOgIEinx0Dto94TB= hUNxkmu2h2KiO5ZQ46z5h_E$ for graphic product...

ATTN...WFO...HGX...JAN...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32279211 32069174 31219173 30399213 29919256=20
29559297 29489403 29509452 30089430 30329421=20
30769397 31419340 31809308 32219254=20

=3D =3D =3D
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AWUS01 KWNH 092201
FFGMPD
MSZ000-LAZ000-TXZ000-100400-

Mesoscale Precipitation Discussion 1146
NWS Weather Prediction Center College Park MD
459 PM EST Sat Nov 09 2024

Areas affected...south-central LA and surrounding portions of
Upper TX Coast and southwest MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 092200Z - 100400Z

Summary...Deep tropical moisture will remain support of high
rainfall rates (of 1-2"/hr) with additional 6-hr totals of 3-6"+
likely. Locally significant flash flooding is expected to
continue, and overall coverage of flooding is likely to become
more numerous to widespread.

Discussion...A wide band of rainfall with embedded heavier showers
has persisted over the past several hours along a surface trough
and ahead of a stalling cold front. Deep layer tropical moisture
remains in place over southwestern LA and surroundings (in
association with southwesterly low to mid level moisture transport
from Tropical Storm Rafael), as indicated by precipitable water
levels of 2.1-2.3 inches (per CIRA advected layered precipitable
water imagery and RAP mesoanalysis). This tropical moisture is
well above the 90th percentile (per experimental ALPW sfc-850mb
and 850-700mb percentiles and LCH sounding climatology), and much
more typical of late August to early September. While instability
remains the primary limiting factor (limiting peak rainfall rates
to 1-2"/hr), 250-500 J/kg of SB/ML CAPE has been sufficient for
sustained heavy rainfall. Going forward, convection may continue
to slowly shift to the southeast (depsite the front stalling near
the LA/TX border), as SB CAPE has risen to 500-1000 J/kg over
south-central LA and southwest MS. Deep layer shear has also
increased a bit (to 25-35 kts), which should continue to be
supportive of at least embedded organized updrafts (with
diffluence aloft also improving with the right-entrance region of
a broad 75 kt jet streak at 250 mb). And with deep layer flow as
low as 15 kts, slow storm motions will continue to support a
mesoscale setup capable of locally significant flash flooding
(particularly over areas that have already received as much as
3-6" of rain over the past 6-12 hours).

Updated CAM guidance (18z HREF suite) remains supportive of
additional significant to extreme rainfall totals over the next 6
hours (HREF 40-km neighborhood probabilities for 5" exceedance
threshold, also corresponding to the 10-yr ARI, as high as 50%),
suggesting the potential for additional localized amounts of 3-6"+
(through 04z). Much of this rainfall may occur near the already
hard hit region in and around Alexandria, though propagation
towards higher instability (south and east) appears to be a more
favorable outcome (as suggested by several HRRR runs, as well as
the ARW/ARW2/FV3 members of the HREF). Locally significant (to
even extreme) flash flooding remains possible, conditional upon
the rainfall axis remaining stalled over southwestern and central
LA. Should the rainfall axis eventually shift towards the south
and east, then additional numerous (to possibly widespread)
instances of flash flooding will shift in tandem.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!58w_B5qH0gL7vkdnmlE6WNLKVuAaAyq5k-4rq9x2zYAyFF1sCaM890kvNXRJFgTDXw3J= f9XVGoaIOqodXgt3k1-IZlQ$ for graphic product...

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32009189 31859111 31459090 30629139 30049208=20
29699262 29599388 29619424 29939427 30429390=20
30979347 31309313 31809265 31969237=20

=3D =3D =3D
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AWUS01 KWNH 100328
FFGMPD
MSZ000-LAZ000-TXZ000-100900-

Mesoscale Precipitation Discussion 1147
NWS Weather Prediction Center College Park MD
1027 PM EST Sat Nov 09 2024

Areas affected...Southwest to Central Louisiana...

Concerning...Heavy rainfall...Flash flooding likely

Valid 100330Z - 100900Z

SUMMARY...Stationary axis of isentropic ascent/stationary tropical
showers likely to maintain ongoing flash flooding across central
Louisiana into the middle overnight period.

DISCUSSION...Most meteorological parameters are continue to reduce
with time; temperatures are coming down with loss of day-time
heating and low level moisture has dropped into the low 70s, so
instability is limited to this limited area of mid 70s over low
70s Tds, with MLCAPE in the 500-1000 range. RADAR and GOES-E
3.9um along with observations from VWP and surface obs suggest,
easterly flow is starting to slack over the southern Bayous of
central LA and adjacent Gulf slowly reducing deeper layer
convergence along the rainfall reinforced cold front. Still, this
is weak WAA over a modestly steep frontal slope to continue to tap
weak convective development and moisture flux to support 1.5-2"/hr
rates, given the total PWats remain near record values in the low
2" range. Storm related outflow/isallabaric may result in a few
embedded narrow cored cells that may occasionally tick above
2"/hr.=20=20

GOES-E WV shows cluster across SW to central LA remains at the
nose of a split in upper-level flow/diffluence from anticyclonic
outflow jet from Rafael over the northern Gulf and the
cyclonically curved polar jet across E TX into AR. This helps to
pull/stretch convective cores toward the northeast with weak
inflow, balance southeast propagation from inflow and slow
north-northeast cell motions to allow for very slow cell motion
with very weak northeastward motion along the isentropical
boundary and already flooded/lowered FFG values into far SW MS.=20
Given the compromised soils the additional 2-3" with localized 4"
maxima (in the embedded convective cores) will likely continue to
result in rapid inundation/flash flooding that is occurring from N
Calcasieu to Concordia parish.=20=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-67ABM8ikrGdxIgEEnhMvIWna6qG-GpnX7ZbjtCy0sV7uKxnepzGDVrbq26swO1r9aTH= F-EwAza0zYszhj4GLMUu1yo$ for graphic product...

ATTN...WFO...JAN...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32149228 32009174 31699148 31459150 31049181=20
30609239 30319287 30159341 30399367 30859365=20
31209353 31789309=20

=3D =3D =3D
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AWUS01 KWNH 100755
FFGMPD
LAZ000-101200-

Mesoscale Precipitation Discussion 1148
NWS Weather Prediction Center College Park MD
255 AM EST Sun Nov 10 2024

Areas affected...Central Louisiana...

Concerning...Heavy rainfall...Flash flooding possible

Valid 100800Z - 101200Z

SUMMARY...Stationary isentropic boundary starting to dislodge from
anchored position. Lingering scattered showers may intersect
compromised soils/flooded areas to maintain localized flooding
conditions over the next few hours.

DISCUSSION...Regional RADAR loop shows stationary isentropic
ascent boundary has recently encountered an increase in low level
winds from 15-20kts to 20-25kts. This increase has allowed for
the stable balance over the last 4-6hrs resulting in 6-12" of
rainfall over N Allen/S Rapides Parishes to finally support an
additional 3-5kts of propagation to the southeast. In addition,
CIRA LPW and RAP TPW analysis suggest air within the increased ESE
and SE flow is also starting to dry realitive to the peak core of
moisture which is currently being ingested allowing for at least
one more good surge of enhanced rainfall rates across Evangeline
parish. Rates of 2-2.5" are likely to be short-lived maybe for
1-1.5 more hours before further evaporating.=20=20

Recent HRRR solution appears to be catching on the trend noted in
RADAR/GOES-E SWIR with increased aggitated Cu along the stationary
front across E TX into NW LA as well as tropical offshore cells
along the outer edges/convergence bands of Rafael. ARW/ARW2
solutions help with this devoltuion as well though timing remains
a bit slow (typical of bias). Still, scattered showers in the
vicinity of the saturated/flooded soils and with ample moisture,
additional .5-1" totals may help maintain/prolong the flooding
across central LA; as such, flash flooding remains possible for
the next 3-4 hours, with reducing probability in time.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5n9DS4WF82ijCc_htERuSdOwShCYM6FBvP0XdWF8DBPlNH1hcbvZ8Yup3FsvOqK22lB-= VkmmwyX8_hcqfu1VNvKp_QI$ for graphic product...

ATTN...WFO...JAN...LCH...SHV...

ATTN...RFC...LMRFC...NWC...

LAT...LON 31809201 31549169 31329167 30979182 30649193=20
30309213 30309307 30539342 30819334 31239300=20
31709237=20

=3D =3D =3D
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AWUS01 KWNH 101245
FFGMPD
MSZ000-LAZ000-101613-

Mesoscale Precipitation Discussion 1149
NWS Weather Prediction Center College Park MD
744 AM EST Sun Nov 10 2024

Areas affected...Central LA into Southwest MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 101243Z - 101613Z

Summary...A localized flash flood risk will continue across
portions of central Louisiana and southwest Mississippi into mid
morning.

Discussion...Radar imagery indicates heavy rainfall cores are
persisting a bit longer than anticipated over portions of central
LA into southwest MS this morning. The 12z sounding from New
Orleans is indicative of the upstream environment feeding into
this axis of rainfall...and it shows a saturated profile up to
500mb with PWs around 2.1". The sounding dries significantly above
500mb, but a moist and skinny CAPE profile below that continues to
support efficient warm rain processes. Thus despite a lack of cold
cloud tops, this activity continues to be capable of hourly
rainfall around 2".

Generally still expecting a downward trend in rainfall coverage
and intensity as the morning progresses. The overall environment
should continue to trend less conducive for excessive rainfall
with lower level convergence gradually weakening and subsidence
and drying continuing to increase in the mid to upper levels. With
that said, recent radar and satellite imagery suggests a localized
flash flood risk will continue for a few more hours. Recent HRRR
runs have started to catch on to a bit more persistence of this
activity, although these 10z and 11z runs are too far northwest
with the rainfall max. Overall expecting additional rainfall of
2-5" over the next couple hours, with the heaviest amounts likely
staying pretty localized in nature.

Chenard

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8etVTqWRZso_51Tg4JcXyMSXXv5seVfeDO1t7GsmYnCzbDxJ7GmpfzHf55OoepDXA0tw= 6EeDJ18SnA13Sqs-81gfnxs$ for graphic product...

ATTN...WFO...JAN...LCH...LIX...

ATTN...RFC...LMRFC...NWC...

LAT...LON 31679099 31629054 31169035 30779045 30399092=20
30299157 30369195 30689223 31189194 31539141=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 101404
FFGMPD
OHZ000-TNZ000-KYZ000-INZ000-ILZ000-102000-

Mesoscale Precipitation Discussion 1150
NWS Weather Prediction Center College Park MD
903 AM EST Sun Nov 10 2024

Areas affected...western and northern KY and surrounding portions
of TN/IN/OH

Concerning...Heavy rainfall...Flash flooding likely

Valid 101400Z - 102000Z

Summary...Additional localized totals of 2-3" likely to lead to
isolated to scattered instances of flash flooding.

Discussion...Streaks of moderate to heavy showers have been
ongoing early this morning across much of western KY into far
southern IN, producing hourly totals of 0.5-1.0" (with 3-hr totals
as high as 2.0-3.0"). This efficient rainfall is occuring within
the warm sector of a mature low pressure system, centered over the
Midwest. A strong low-level jet (40-50 kts at 850 mb) is providing
ample moisture transport into the region, and low-level (925-850
mb) convergence is significant. This convergence is better
visualized via isentropic analysis with upglide most evident on
the 294K and 296K surfaces (centered near 900 mb) at 30-40 kts.
Aloft, the right-entrance region of a 100 kt jet streak is
providing divergence to offset the low-level convergence, and
convection is expected to continue within this zone of highly
anomolous moisture (with PWs near 1.6", indicated to be near the
max moving average per BNA sounding climatology).

While the 00z/06z CAMs mostly indiciate forward-looking 6-hr
totals maximized near 1", the HRRR and FV3 are indicating
localized totals closer to 1-2" (with 06z HREF 40-km neighborhood
probabilities for 2" exceedance as high as 25%). Given that
2.0-3.5" amounts have been recorded over the past 3-6 hrs (already
at or exceeding corresponding FFGs), additional isolated to
scattered instances of flash flooding are considered likely (as
the FLASH CREST unit streamflow response is already fairly robust
from southwest KY to the greater Louisville metro area).

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-V6kMD2POGD-MT7PUplmGTCdCtsrHEG5cB1Br-nKyn-O_zlNukeKKHD2Fd--tScs4jWD= 1r224KkxjUMG8bVTJd5in_M$ for graphic product...

ATTN...WFO...ILN...IND...LMK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON 39328439 38718390 37448548 36198733 36148874=20
36718898 37928762 38478667 38978573=20

=3D =3D =3D
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AWUS01 KWNH 101428
FFGMPD
OHZ000-TNZ000-KYZ000-INZ000-ILZ000-102000-

Mesoscale Precipitation Discussion 1150...Corrected
NWS Weather Prediction Center College Park MD
927 AM EST Sun Nov 10 2024

Corrected for discussion typo

Areas affected...western and northern KY and surrounding portions
of TN/IN/OH

Concerning...Heavy rainfall...Flash flooding likely

Valid 101400Z - 102000Z

Summary...Additional localized totals of 2-3" likely to lead to
isolated to scattered instances of flash flooding.

Discussion...Streaks of moderate to heavy showers have been
ongoing early this morning across much of western KY into far
southern IN, producing hourly totals of 0.5-1.0" (with 3-hr totals
as high as 2.0-3.0"). This efficient rainfall is occurring within
the warm sector of a mature low pressure system, centered over the
Midwest. A strong low-level jet (40-50 kts at 850 mb) is providing
ample moisture transport into the region, and low-level (925-850
mb) convergence is significant. This convergence is better
visualized via isentropic analysis with upglide most evident on
the 294K and 296K surfaces (centered near 900 mb) at 30-40 kts.
Aloft, the right-entrance region of a 100 kt jet streak is
providing divergence to compliment the low-level convergence, and
convection is expected to continue within this zone of highly
anomalous moisture (with PWs near 1.6", indicated to be near the
max moving average per BNA sounding climatology).

While the 00z/06z CAMs mostly indicate forward-looking 6-hr totals
maximized near 1", the HRRR and FV3 are indicating localized
totals closer to 1-2" (with 06z HREF 40-km neighborhood
probabilities for 2" exceedance as high as 25%). Given that
2.0-3.5" amounts have been recorded over the past 3-6 hrs (already
at or exceeding corresponding FFGs), additional isolated to
scattered instances of flash flooding are considered likely (as
the FLASH CREST unit streamflow response is already fairly robust
from southwest KY to the greater Louisville metro area).

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8kT9qV7btrgtkYBd1C7SbGtvmidrZdv1xjSrmZgpfU_NHz_bkoTDFKVb27nXPw88LUi2= 2Q6xpP_uJSAAjkkNOh15F2M$ for graphic product...

ATTN...WFO...ILN...IND...LMK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON 39328439 38718390 37448548 36198733 36148874=20
36718898 37928762 38478667 38978573=20

=3D =3D =3D
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AWUS01 KWNH 122128
FFGMPD
ORZ000-WAZ000-130900-

Mesoscale Precipitation Discussion 1151
NWS Weather Prediction Center College Park MD
427 PM EST Tue Nov 12 2024

Areas affected...western WA

Concerning...Heavy rainfall

Valid 122123Z - 130900Z

Summary...Areas of heavy rain will move into western WA this
evening and overnight with occasional rainfall rates in excess of
0.5 in/hr, especially across the Olympics. Peak 12 hour rainfall
totals of 2 to 4 inches are expected across the favored upslope
regions of the Olympics and Willapa Hills.

Discussion...GOES West water vapor imagery at 21Z showed an upper
level trough centered about 900 miles west of the Pacific
Northwest coast, containing embedded shortwaves. One of the more
notable shortwaves/vorticity maxima was reflected in the visible
imagery with a well-defined swirl near 45N 143W. Surface and
visible satellite data identified an occluded cyclone extending
outward from a surface low near 50N 140W and widespread cloud
cover extending downstream from the associated IVT plume ahead of
the cold front.

As the upper trough and embedded vorticity maxima continue to
advance eastward through early tonight, a triple point low is
forecast to develop by a consensus of the latest numerical
guidance by 00Z just southwest of 50N 130W with northward movement
overnight. The attendant occluded/cold front will likely remain
progressive toward the south and east, reaching the Olympic
Peninsula in the 06-09Z time frame along with the maximum IVT,
forecast by the 12Z model consensus to near 800 kg/m/s along the
coast. 850 mb winds are expected to peak into the 70-80 kt range
from the SSW within precipitable water values of 1.0 to 1.1 along
the WA coast.

Rainfall intensity will gradually increase in the 00-06Z window
with peak rainfall rates possibly exceeding 0.5 in/hr in the
Olympics prior to 06Z (40-50 percent via 12Z HREF, but adjusted
for the 18Z HRRR and 18Z NAM_nest). Those probabilities of 0.5+
in/hr rates increase to just over 80 percent by 09Z for the
Olympics. The low level moisture transport will favor the highest
rates over SSW facing terrain, including the Willipa Hills,
although the probabilities for 0.5 in/hr in southwestern WA are
generally less than 10 percent for the overnight period via HREF
output. While rainfall intensity will be increasing overnight, the
greatest coverage of higher intensity rainfall will likely come
with the arrival of the frontal boundary though limited
instability may temper maximum rates a bit. Nonetheless, strong
forcing for ascent ahead of the approaching upper trough axis,
including increasingly diffluent flow aloft, should allow for
localized 12 hour rainfall maxima of 2-4 inches across the favored
terrain of western WA through 09Z. These rains are expected to
increase the potential for minor flooding across the region, but
mainly focused into the Olympics.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6EjfNNttL9lCkLUPpgQVfgCmVfv0nDin0tNpJQr3VQormG-WGCa0OU3CDkYBdgjKZXZN= 7UYGW65BPymlwS6HHx2kg60$ for graphic product...

ATTN...WFO...PQR...SEW...

ATTN...RFC...NWRFC...NWC...

LAT...LON 48132389 48022339 47862310 47662299 46932314=20
46282296 46232337 46262403 46472435 46802458=20
47242477 47682501 48112467=20

=3D =3D =3D
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AWUS01 KWNH 130750
FFGMPD
CAZ000-ORZ000-WAZ000-131800-

Mesoscale Precipitation Discussion 1152
NWS Weather Prediction Center College Park MD
250 AM EST Wed Nov 13 2024

Areas affected...Coastal and Cascades Ranges of E WA & E
OR...Northwest CA...

Concerning...Heavy rainfall

Valid 130800Z - 131800Z

SUMMARY...Progressive but potent slug of enhanced moisture flux
along Coastal and Cascade Ranges producing 2-4" totals with
occasional hourly rates to .5"/hr with greatest totals in SW
facing orography increasingly so in SW OR/NW CA.

DISCUSSION...GOES-W WV shows main core of the upper-low just south
of 47N near 132.5W starting to slide northeast with upstream
energy starting to dig the upper-trough, expecting to go more
neutral tilt over the next 6-12hrs as it approaches the West
coast. The 150kt jet core just rounding the base of the trough is
broadening with large cirrus shield. GOES-AMV and RAP analysis
note a split in the jet downstream northeast of the 40N130W
benchmark; this is enhancing broader and more intense upper-level
divergence along the Oregon coastline. Additionally, a weak
inflection is developing in the low levels with upstream
height-falls leading to sharper boundary layer moisture
convergence along and downstream backing the progressive frontal
zone a bit more flat to the mean steering flow and increasing
deeper layer moisture convergence. CIRA LPW notes, 1-1.25" total
PWat in this area where surface and slug of 850-700mb moisture
overlap. Given 60-70kts of 850mb flow (~700-900 kg/m/s IVT),
convergence is going to result in enhanced showers capable of
.5-.6"/hr rates likely to intersect the northwest to central OR
Coastal Range over the next few hours. So while the strength of
orographic ascent will be consistent along the front, this
slightly backed flow ahead of the inflection will have increased
totals compared to the average 2-3" totals, some localized 3-4"
values may occur before midday. Strength of AR and moisture flux
may be supportive enough to bleed through the coastal range with
some enhanced rainfall totals across the western slopes of the
northern and central Oregon Cascades.

To the north western WA...
Post cold front showers will remain widely scattered, and with
steeper lapse rates will support higher but much shorter duration
rainfall across areas with modest 2-3" totals so far through the
event, while NASA SPoRT soil saturation values are higher than
normal, the burst nature is still not likely to result in any
rapid inundation/flashy conditions but maintain above normal
run-off.

South of the inflection across SW OR into NW CA...
The core of the AR moisture stream will remain along/ahead of the
cold front, but will be narrowing as the mid-level moisture slug
slides ashore and surface moisture band narrows/stretches in
width. Height-falls will swing through later in the morning/early
afternoon, but traditionally favorable southwesterly flow into
generally steeper terrain and confluent 45-50kts of 850 flow
around the Cape, prolonged moderate rainfall with streaks of
enhanced showers up to .5"/hr are probable. This is still fairly gentle/typical for the boreal rain forests to handle much of the
rainfall, and while run-off will be enhanced is not likely to
result in any significant concerns that would not be for an
ordinary AR. IVT values will be decreasing with reduced
moisture/low level flow from 800 kg/m/s across the central OR
coast toward 500-600 kg/m/s. Still, traditional orographic ascent
will support spots of 2-3" by 18z.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7uODexacBzF7PVCxHek5wHR6MKxnMQhwIpYoJvfvjup-0Ov8g6M2EFYEquio7vwODp9r= kefoCOKvFOlq7e_FfljxRcM$ for graphic product...

ATTN...WFO...EKA...MFR...PQR...SEW...

ATTN...RFC...CNRFC...NWRFC...NWC...

LAT...LON 49052223 49052156 48412141 46912178 45782182=20
44322201 43042201 42212223 41802250 41082314=20
39922370 39922426 40262453 40672460 41272434=20
41832441 42292464 42812479 43492460 44162434=20
45292434 46312415 47362445 47962475 48452475=20
48192381 47962344 47252329 46952317 46832291=20
47102235 47622223=20

=3D =3D =3D
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AWUS01 KWNH 131111
FFGMPD
MSZ000-LAZ000-131635-

Mesoscale Precipitation Discussion 1153
NWS Weather Prediction Center College Park MD
611 AM EST Wed Nov 13 2024

Areas affected...South-central Louisiana...

Concerning...Heavy rainfall...Flash flooding possible

Valid 131110Z - 131635Z

SUMMARY...Slow moving, efficient cells capable of 2.5"/hr rain
rates. Training profile and upstream redevelopment pose risk of
localized flash flooding with 3-4" totals possible.

DISCUSSION...The remnant low level circulation of Rafael has been
shearing north to south through a deep axis, but has retained a
few convergent low-level bands and fairly robust core of anomalous
deep layer moisture. Aloft, large scale ridge over-top the
circulation is also being stretched/amplified along/ahead of
height-falls coming out of the central Plains. As a result, weak
850-500 DPVA is providing ascent and low level wind response to
increase surface to boundary layer moisture convergence with 25kts
of 850mb flow from the southeast cyclonically converging at the
apex/downshear of the wave just south of central LA coastline. A
core of enhanced inability also exists through this moisture
transport axis with 2000-2500 J/kg of SBCAPE to provide strength
to vertical development over the next few hours. Within this axis,
CIRA LPW shows core of enhanced moisture with 1-1.1" in the
sfc-850, and over .5" in the 850-700mb layer. Both are near the
99th to maximum percentile for climatology in November.

Current GOES-E SWIR/10.3um EIR along with RADAR denotes initial
convective development near Marsh Island lifting north through the
best convergence/confluence axis. Cells are initially weaker with
1-1.5"/hr rates, but with increasing DPVA/strengthening of the
winds strengthening convergence, coverage of cells capable of
2-2.5"/hr are likely to become more numerous as winds strengthen
to 20-30kts by 13-14Z. Deep layer moisture is confluent into
increasing FGEN/moisture axis, deformation zone that extends into
central LA and up the Lower MS River Valley/Delta Region. As
such, a favorable upstream convergence should support upstream
development for potential training/repeating into a slowly (0-5kt)
eastward drifting moisture gradient. Modest effective bulk shear
in the 25-30kt range, suggest some weak rotation to the updrafts
could further slow forward propagation resulting in localized axis
of 2-4".=20

While current trends suggest most cells will remain near the coast
in the near-term, mid-morning could see further downstream motions
toward areas of recent heavy rainfall and saturated upper soil
depths...while FFG value have rebounded, 0-40cm saturation ratios
remain over .65 which is the 90th-95th percentile, suggesting
increased runoff in more likely north of I-10 into central LA.=20
Still, coastal regions may be more receptive and scattered flash
flooding/rapid inundation is considered possible through 16z.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7FmBQaNyYyaxEGU7iJdSVbg2p9LNhtvNU1_Cen-a4I8nvgWLcQ7NlSXTASh6rV2FLbSV= x2yeN2Tusbdc0jS-_jVQtK4$ for graphic product...

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...NWC...

LAT...LON 31769219 31579159 30609114 29649066 29069024=20
28929090 29369197 29489241 29539295 29939321=20
31079309 31539277=20

=3D =3D =3D
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AWUS01 KWNH 131633
FFGMPD
MSZ000-LAZ000-ARZ000-132130-

Mesoscale Precipitation Discussion 1154
NWS Weather Prediction Center College Park MD
1132 AM EST Wed Nov 13 2024

Areas affected...south-central/southeastern LA into southwestern
MS

Concerning...Heavy rainfall...Flash flooding likely

Valid 131630Z - 132130Z

SUMMARY...Training and repeating of thunderstorms should maintain
at least localized flash flooding from south-central and
southeastern LA into southwestern MS. Localized rainfall rates of
2 to 3+ in/hr will remain possible, falling atop locations which
received heavy rain in recent days. Additional totals of 2 to 4
inches will be possible (perhaps locally higher) through 22Z, but
the coverage of these higher rainfall totals should remain
low/spotty.

DISCUSSION...Areas of training thunderstorms in and around the
Lafayette metro have resulted in numerous reports of 4-6 inches of
rain over the past 4-5 hours with hourly rainfall as high as 4
in/hr. Heavy rainfall has been focusing along an inverted trough
or weak frontal boundary extending northward from a weak/elongated
low located just south of Marsh Island with the coldest cloud tops
over southwestern MS into adjacent areas of LA at 16Z. 12Z
soundings from LCH and LIX combined with Layered PW Imagery from
CIRA showed the bulk of the nearly 2 inch precipitable water
values are focused below 700 mb, with a fair amount of dry air in
the middle and upper troposphere.

Over the next 3-6 hours, the elongated area of low pressure/shear
axis across LA is expected to slowly but steadily get pushed east
ahead of a large-scale 700-500 mb trough moving east across the central/southern Plains. Surface to 850 mb convergence will shift
into the southwestern quadrant of MS and southeastern LA through
21Z where MLCAPE of 500-1500 J/kg is forecast to reside (highest
to south) via the latest RAP guidance. Areas of training
thunderstorms are expected to continue with 2 to 3+ in/hr rainfall
rates at times, overlapping with areas that received heavy rain
over the weekend and may remain hydrologically more sensitive to
runoff.

Farther east, a low level axis of convergence/leading edge of
moisture return to the south of an East Coast surface ridge has
been producing a few showers and thunderstorms. This area of
convection is likely to shift east as well in a mostly progressive
fashion, but an isolated threat for short term training could
result in urban flooding for the New Orleans metro over the next
few hours.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4tLj5AP-59ex4RZwax1shPABq6k0zjoqsPm_gIICJlTSMXmSSdewwAoW9g_QzwMRn-Li= Em8Cr5v2lBAGXPU1O0pzBEM$ for graphic product...

ATTN...WFO...JAN...LCH...LIX...MEG...

ATTN...RFC...LMRFC...NWC...

LAT...LON 33859027 33688989 33368956 32838930 31428951=20
30298983 29499014 29689133 30039181 30799201=20
32179173 33329125 33839080=20

=3D =3D =3D
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AWUS01 KWNH 132202
FFGMPD
TNZ000-KYZ000-INZ000-ALZ000-ILZ000-MSZ000-140400-

Mesoscale Precipitation Discussion 1155
NWS Weather Prediction Center College Park MD
501 PM EST Wed Nov 13 2024

Areas affected...MS River Valley into northern MS, western TN/KY,
southwestern IN

Concerning...Heavy rainfall...Flash flooding possible

Valid 132200Z - 140400Z

SUMMARY...Training thunderstorms across the lower MS/OH Valleys
will be capable of 1 to 2+ in/hr rainfall rates and localized
totals up to 3 inches through 04Z. Isolated flash flooding may
occur as a result.

DISCUSSION...Infrared satellite and radar imagery showed scattered
showers and thunderstorms across the lower OH and MS Valleys into
portions of central MS/western AL as of 2130Z. Forcing for ascent
included lift ahead of a mid-upper level trough moving east
through the central/southern Plains, with cells near and east of a
low level (925-850 mb) confluence axis located across the lower MS
Valley, which also extended northward into the lower OH Valley
although not as strongly when compared to locations farther south.
Low level warm advection was also contributing to heavier rainfall
across the IN/KY border, located at the leading edge of 50-60 kt
850 mb winds via VAD wind and short term RAP forecast data.
Instability was somewhat limited however, with 500 to 1000 J/kg
MLCAPE confined to central MS and elevated CAPE in excess of 500
J/kg in pockets farther north into western KY via 21Z SPC
mesoanalysis data.

Water vapor imagery showed the mid to upper level trough over the
central Plains acquiring a negative tilt which wil continue east
into the overnight. Out ahead, diffluent flow across the lower OH
Valley will aid in ascent with the slow eastward moving axis of
low level confluence likely allowing for repeating/training rounds
of heavy rain which could allow rates to reach into the 1-2 in/hr
range through early overnight.

To the south, across central/northern MS into western TN, locally
higher instability should support greater intensity rainfall with
ascent aided within the right entrance region of a 100-110 kt
upper jet max located east of the advancing upper trough. The axis
of low level confluence located in MS/western TN is expected to
translate slowly but steadily toward the east over the next few
hours which should limit training potential, however, periods of
short-term training will still be possible, including the
potential for more organized cells due to the combination of
greater instability and favorable shear profiles. Rainfall rates
of 1 to 2+ in/hr cannot be ruled out along with isolated areas of
flash flooding through 04Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7OHFwLbNh11sOpNmvwiFeD7aeQcr4aO1WoVQgLU7WPVyU2fYz_h7LYtEB3Ox3Uk0p2DJ= SxMwR_xY7W8XO8rqLXmkJxM$ for graphic product...

ATTN...WFO...BMX...HUN...IND...JAN...LMK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...SERFC...NWC...

LAT...LON 38778598 38258572 37498613 35788696 34348750=20
32798866 32829016 33219054 34799016 36148939=20
37438836 38618692=20

=3D =3D =3D
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AWUS01 KWNH 140256
FFGMPD
FLZ000-ALZ000-MSZ000-140830-

Mesoscale Precipitation Discussion 1156
NWS Weather Prediction Center College Park MD
955 PM EST Wed Nov 13 2024

Areas affected...Eastern MS...Much of AL...Far Western FL
Panhandle...

Concerning...Heavy rainfall...Flash flooding possible

Valid 140255Z - 140830Z

SUMMARY...Intense thunderstorms capable of a quick sub-hourly 1-2"
near the front pose mainly urban flash flooding threat, while
slower moving more scattered supercells within the Coastal Plain
may result in a axis or two of 3-4" totals with similar localized
flash flooding concerns through early overnight period.=20

DISCUSSION...GOES-E WV suite depict slightly below average closed
low crossing IA/MO with a well defined cold front/warm conveyor
belt system across the Lower Ohio, Western Tennessee River Valleys
extending south into MS where it is interacting with enhanced deep
layer moisture and remnant low level circulation energy of ex-TC
Rafael. CIRA LPW and RAP analysis denote enhanced tropical
moisture and higher than normal theta-E air extending northward
along a core of 30-35kt 850 southerly low-level jet. However, the
deepest moisture and unstable air remains further south, generally
in the lower 2/3rds of eastern MS into western AL, with maximum
unstable air of 2000-2500 J/kg along the central Gulf Coast.=20
Strong height-falls and right entrance ascent to 3H 100 kt Jet in
the central MS Valley is providing the oblique but sufficient
intersection with the cold front to generate convective cells from Starkville/Columbus MS southward to the tail of the
front/inflection near the apex of the remnants of Rafael east of
McComb. Given the stronger LLJ/divergence aloft remains displaced
from best moisture/instability, cells still remain potent with
capability of generating 1-1.5" total though with waning
instability, updrafts continue to diminish from north to south
over the next few hours. Still, there are urban targets along
this track and with the sub-hourly totals near or over 1hr FFG
particularly north and west AL and west central MS remains at low
end risk for localized flash flooding for the next few hours.

Further south, slightly backed flow as a result of the sheared
inflection from ex-Rafael, moisture/instability axis is extended a
tad eastward. Effective bulk shear is stronger to the north but
given stronger SBCAPEs and backed low level flow, the potential
for widely scattered supercells remains possible. Slower eastward
propagation combined with natural slowing of rotating cells,
allows for increased duration. Combined with broader updraft and
enhanced directional convergence at the base of the updrafts,
greater moisture flux of higher surface to 850mb moisture
(gnerally 1.5"-1.75 per CIRA LPW through 700mb) will increase
rainfall efficiency and localized duration. Rates of 2-2.5"/hr
with localized spot of 3"+ possible in 1-2 hours pose a flash
flood risk, especially given recent above average rainfall per
AHPS and lowered FFG values in S AL. However, currently the best
candidate cells is along/just south of Mobile Bay and in Greene
county MS moving into Washington AL. As such, flash flooding
remains possible through the early overnight period as well across
S AL into far W FL panhandle.=20=20

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!65FWgPo9OegZLuChIQEmJWRU1VncI7-KOLiEe1jSEbUXsAKI5p6t-XGTHad_VgZdlOlP= ghtJxuufFgiQ4y6sjTUHibM$ for graphic product...

ATTN...WFO...BMX...HUN...JAN...MOB...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 34268695 34178620 33838592 33308574 32408606=20
31518649 30568702 30258757 30218794 30368823=20
30738837 31038898 31348964 32108965 33258859=20
33948776=20

=3D =3D =3D
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AWUS01 KWNH 182157
FFGMPD
MSZ000-LAZ000-TXZ000-190400-

Mesoscale Precipitation Discussion 1157
NWS Weather Prediction Center College Park MD
455 PM EST Mon Nov 18 2024

Areas affected...Far Southeast TX...Southwest to Central LA

Concerning...Heavy rainfall...Flash flooding possible

Valid 182200Z - 190400Z

SUMMARY...An increase in coverage of showers and thunderstorms can
be expected going into the evening hours. Heavy rainfall rates and
potentially some areas of cell-training may foster some localized
potential for flash flooding.

DISCUSSION...As a deep upper-level trough pivots northeastward
through the central Plains and toward the Midwest, a cold front
will be gradually approaching the northwest Gulf Coast region.
This front will be interacting with a very moist and increasingly
unstable airmass out ahead of it this evening, and the result is
expected to be an increase in the coverage of heavy showers and
thunderstorms.

PWs are quite high right now across southeast TX with values near
or slightly above 2 inches, and these magnitudes are as much as 2
to 3 standard deviations above normal for this time of the year.
Meanwhile, MLCAPE values have risen to as much 1000 to 1500 J/kg
and thus a moderate level of buoyancy has already pooled ahead of
the front with the aid of daytime heating.

A fairly strong southerly low-level jet of 30 to 40+ kts will be
maintaining somewhat enhanced moisture transport off the Gulf of
Mexico ahead of this front this evening. This coupled with the
level of instability and favorable bulk shear should yield
relatively organized bands or clusters of convection, including
potentially some supercell activity, that will be capable of
producing rainfall rates of 1 to 2 inches/hour. Initially the
activity will be more focused over areas of far southeast TX, but
should in time concentrate increasingly over southwest to central
LA.

Some of the more organized activity may involve some cell-training
as the convection becomes aligned with the deeper layer mean flow,
and this may result in the potential for locally excessive totals.
The 12Z/18Z HREF guidance supports some 2 to 4 inch rainfall
amounts with isolated heavier totals. A localized and mostly urban
flash flood threat will exist as these bands of convection come
through this evening.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6jucQIqEYwpxCvflmYFiKiE8VFtMqgbz0oaNbKbL_kmV0P55GzA3aCGc1dkx8VLC1nES= J4HizpGEPbfo3Q_5v0bbbow$ for graphic product...

ATTN...WFO...JAN...LCH...LIX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32289212 32109155 31229155 30039244 29619285=20
29709339 29649395 29909426 30469430 31049394=20
32059292=20

=3D =3D =3D
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AWUS01 KWNH 191344
FFGMPD
FLZ000-ALZ000-MSZ000-LAZ000-191900-

Mesoscale Precipitation Discussion 1158
NWS Weather Prediction Center College Park MD
843 AM EST Tue Nov 19 2024

Areas affected...Eastern LA...Southern MS...Southern AL...Far
Western FL Panhandle...

Concerning...Heavy rainfall...Flash flooding possible

Valid 191345Z - 191900Z

SUMMARY...Highly anomalous deep moisture and strength of flux
allowing for efficient rainfall production with progressive
pre-frontal trough. Embedded slower moving rotating updrafts will
enhanced localized rainfall totals of 3-5" resulting in possible
flash flooding.

DISCUSSION...GOES-E WV suite depicts a large scale closed low
dominating the northern Plains with negative tilt lower scale wave
moving through the western Great Lakes, this is driving a very
strong mid to upper level jet across the Mississippi Valley which
in turn is spurring an very broad and strong low-level jet out of
the Tropics into the central Gulf of Mexico intersecting the
central Gulf Coast. CIRA LPW shows nose of 1-1.25" surface to
850mb starting to near the southern TN boarder while as broad as
central LA to western FL Panhandle. Combined with 40-45kts of
southerly 850mb winds and 60-90 degrees of directional
convergence; brings moisture flux values into the 99th and maximum
percentile rankings over a vast area of the Deep South.

An embedded shortwave/inflection can be analyzed through depth
across S MS at the broad left entrance of the 120kt polar jet
across AR/N MS, but also a weak diffluence region across S MS/AL
in the wake of an exiting sub-tropical jet streak that is rounding
the downstream large scale ridge into the Southern Appalachians.=20
So while the height-falls are driving the cold front forward,
there is weak surface to 850mb wave in S MS that is backing
low-level flow and increasing flux convergence in that region, as
well as further upstream in the coldest tops/highest unstable air
across the mouth of the MS River and northern Gulf of Mexico. The
instability gradient is along the Gulf Coast and as a result
strongest cells/tops to -83C have been measure and with moisture
values of 2.5-2.75", rates of 3"+/hr are possible across SE LA for
the next hour or so. Near the surface inflection, weaker
instability but solid flux convergence and increased bulk shear
will allow for short-term efficient rainfall production to 2"/hr;
with the vast majority falling in a sub-hourly manner given
forward progress. This should result in possible flash flooding
for urban and prone areas across E LA into S MS/S AL over the next
few hours as the pre-frontal convergence zone slides east.=20

As the morning progresses, bulk shear values increase over 40kts
along and east of the inflection as it slides slower to the east
in the further enhancing right entrance (increasing to 130-140kts)
300mb jet. This will slow the frontal zone as well, and allow for
some modest/weak instability to build back west to the boundary.=20
Embedded rotating updrafts have a higher probability of occurring
and with backed/increased directional moisture flux and reduced
forward speed/propagation... downdrafts with capability to produce
2.5-3"/hr rates may occur. Recent HRRR and 00z Hi-Res CAMs hint
at this solution across the lower 2-3 rows of counties in
MS/AL...combine this localized increase of 2-4" with the preceding
progressive but intense showers on the pre-frontal trough and
localized 3-5" totals become increasingly possible. Given the
bulk of unstable air remains offshore, there is some reduction in
confidence that updrafts will be strong enough to overcome the
increased bulk shear to support these increased rates. However,
the potential remains and would be the most likely driver to
potential flash flooding events even into rural areas where FFG
values of 3-4"/3hrs are more representative of soil conditions.=20=20
As such, flash flooding is considered possible through the morning
into early afternoon.


Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!82ah6Q-ckqRNkevsaGmwb3_q2Kwc4cqt7J5U3jZ97nTD6YePil4ppAX3h0_tzJL-7b3d= Z06AH1XwYUP9HIoSnMGcCRc$ for graphic product...

ATTN...WFO...BMX...JAN...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 32648645 32208539 30938530 30128581 30188632=20
30098773 29628864 29068883 28878931 29139023=20
30578966 31758890 32518776=20

=3D =3D =3D
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AWUS01 KWNH 192003
FFGMPD
CAZ000-ORZ000-WAZ000-200630-

Mesoscale Precipitation Discussion 1159
NWS Weather Prediction Center College Park MD
302 PM EST Tue Nov 19 2024

Areas affected...Coastal Ranges of WA, OR and Northwest CA...

Concerning...Heavy rainfall

Valid 192000Z - 200630Z

SUMMARY...Approach of occluded/cold front into WA/OR after 00z;
start of prolonged moderate rainfall with strong Atmospheric River
into SW OR/NW CA...

DISCUSSION...GOES-W shows a classic evolution of a rapidly
deepening 'bomb' cyclone just north of 45N132W, with impressive
comma-head baroclinic shield expanding along the NW and N side
while a clear slot/descending branch over the SW and southern
hemispheres. Central pressures have gone from 1014mb to estimated
955mb from OPC in the last 24hrs. A broad sub-tropical jet cirrus
canopy with subtle ridging at the apex of the cold front
42.7N129.5W indicates the anticyclonic rotor of the nose of the
140kt jet directed toward the central OR coast. Clearing aloft,
has allowed a view of narrow convective elements along the
occluded portion of the front where steep lapse rates/CAA aloft
support a narrow ribbon of 500-750 J/kg of SBCAPE. CIRA LPW shows
sfc-700mb layers remain very narrow stretched along/ahead of the
cold front, before broadening to a broader wedge of slightly above
average moisture values south of 38N and west of 134W,
approximately delineating a warm front. Enhanced 700-500
moisture hugs the entire length of the mid to upper level jet and
portion of the cold front (WSW to ENE orientation) that parallels
(generally west of 130W). As such, total PWats of 1-1.25"
southwest of the warm front are showing very high moisture flux on
60 to 90kts of 850mb southwesterly flow helping to build IVT
values of near 900-1000 kg/m/s.

This front will continue to advance quickly toward the coast over
the next few hours with similar orientation/northward expansion of
the warm front. Further strengthening of the occluded low will
bottom out toward mid to upper 940mb range but start a cyclonic
loop reducing the surface to boundary layer impetus and expand the
occluded front in a northwesterly manner. As such, elevated
convection will reduce in forward speed reaching the coast and
with further narrowing influences and upper-level jet expanding
further eastward into the central OR...convective elements will
become more fractured in nature only to increase orographic ascent
light rainfall from 1/20th to .1" per hour with scattered streaks
of .33-.5"/hr resulting in spotty 1-1.5" totals along favored
southwest facing coastal ranges from central OR northward.

Further south, the leading edge of heavy rainfall/WAA should be
arriving in the 03-06z time frame toward Southwest Oregon and
Northwest California. IVT values in the 400-500 range will
increase toward 700 kg/m/s by 06z. Weakly unstable air near the
triple point and just upstream along the cold front in the warm
sector could see enhancement of rates from .5-.75"/hr along or
just offshore by 03z. HREF 1"/hr probability reach 50% along the
coast by 06-09z, though 1"/3hr values are over 75% with spots
offshore near 100% nearing the NW CA coast. At this point, there
is not likely to be sufficient coverage/intersection with coastal
locations to result in excessive rainfall/flash flooding...though
may become more of a risk after 06z.

As such, will leave the hazard tag as only Heavy Rainfall expected
for this MPD; but this rainfall south of central OR will only set
the stage for upcoming likely significant rainfall across the area
over the next few days. Please keep attune to further MPDs, AHDs
from the National Water Center and flooding/hydrological
advisories and statements from local forecast offices over the
coming days.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-aoHmH-pg9_tbypJXyH5IpgccCd57z5Fbcvw0YTle1efs_OIdqJmrTmfGQpuSwemuzuD= E2CC-hYKQhjX9vo5iH--CfA$ for graphic product...

ATTN...WFO...EKA...MFR...PQR...SEW...

ATTN...RFC...CNRFC...NWRFC...NWC...

LAT...LON 48362483 47992415 47312359 46222336 44762359=20
43682404 42632396 41762381 41132348 40532340=20
40082363 39962415 40302456 40942483 41312460=20
42102453 42852471 43562456 45212426 46672449=20
47422475 47872490 48102498=20

=3D =3D =3D
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AWUS01 KWNH 201309
FFGMPD
CAZ000-ORZ000-202100-

Mesoscale Precipitation Discussion 1160
NWS Weather Prediction Center College Park MD
806 AM EST Wed Nov 20 2024

Areas affected...Northern California... Far Southwest Oregon...

Concerning...Heavy rainfall

Valid 201300Z - 202100Z

SUMMARY...Solid, persistent Atmospheric River to continue
throughout the morning into afternoon. Typical .25-.33"/hr rates
may occasionally tick up to .5" for an hour or so occasionally
with localized embedded pulses across Southwest facing terrain.=20
Solid 2-4" for terrain with 1-2" for lower slopes/valleys by 21z.

DISCUSSION...GOES-W SWIR and regional RADAR mosaic, shows the back
edge of the atmospheric river nearing the OR/CA boarder as the low
to mid-level drying under the core of the upper-level jet
continues to press the occluded front across W WA through to the
SW OR coast. The triple point appears in a traditional location
just north of Cape Mendocino before it jumps south as the front is
expected to reach the CAPE over the next few hours. While the
near record deep cyclone continues to slowly wobble north, there
remains still a bit of height-falls to allow for the front to
continue a slow sag southward. Well upstream, a subtle shortwave
near 35N and 140W is starting to amplify with downstream
baroclinic leaf forming between 140 and 130W; but that is well
away off, but will likely start to have some influence with
localized shortwave ridging and finally stall the southward
progression of the front, likely between 21-00z.=20

Southward drift relative to the coast remains a few miles an hour,
the core of 50-65kts of slightly cyclonic 850mb flow into
southwest facing orography will shift from S Humbolt county
currently, through Mendocino, likely reaching Sonoma and far
northern Marin county by 18-21z. With exiting of stronger
height-falls, winds will tapper but only slightly and remain at
50kts in the 850mb layer. CIRA LPW and RAP analysis show core of
highest sfc-700mb is now nosing into the coast and rain-rates are
likely to increase from the .25-.33" to .5"/hr at that nose for a
few hours before slipping south (with lingering .25-.5"). HREF
.5"/hr probability remains well above 75%, with a secondary maxima
along the lower slopes of the northern Sierra Nevada Range. The
strength of the WAA will likely keep freezing levels lifting up
from 2000 to 5000 ft throughout the day. Allowing the lower
slopes to see similar rainfall rates/impacts nearing 2-4" by 21z.=20
Valleys will obviously see much less, but still beneficial 1-2"
are probable (with exception of directly in rain-shadow of the SW
facing peaks).

As the AR plume, reaches its southward extent in the 18-00z time
frame, winds will still further slack, but PW will be increasing
as deep layer flow becomes unidirectional and each layer
contributes to near 1.5" (still well offshore); basically, as the
strength of flow decreases it will be bolstered by increased total
moisture and so rates are likely to remain fairly steady
throughout with only those localized embedded pulses reaching
above .5"/hr. While the soils continue to further saturate, with
increasing run-off as it does so; overall rates still do not
likely reach flash flooding concerns quite yet, but localized
slower rise flooding and nuisance/urban flooding will remain
probable.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-NpsoHZsM_OUATdSdbSPD3yFgX8RZicD4HuiKTwQaIY1LQgQKrtdKEVYNtLSPWdFY0i2= xVOZWeZWUOprtv22DV40tsM$ for graphic product...

ATTN...WFO...EKA...MFR...MTR...STO...

ATTN...RFC...CNRFC...NWRFC...NWC...

LAT...LON 43012444 42922411 42582386 42142365 41592353=20
41102336 41032265 40992258 40992209 40622192=20
40152181 39602136 39232098 38702111 38332155=20
37832268 38392350 39202397 39972440 40582462=20
41222436 41822441 42262459 42652467 42972457=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 202030
FFGMPD
CAZ000-210600-

Mesoscale Precipitation Discussion 1161
NWS Weather Prediction Center College Park MD
329 PM EST Wed Nov 20 2024

Areas affected...Northern California...

Concerning...Heavy rainfall

Valid 202030Z - 210600Z

SUMMARY...Strong, persistent heavy rainfall signal continues into
north-central coastal Range and starting to bleed over to the
northern Sierra Nevada range with times of .5-.75"/hr rates and
additional 3-4" totals by 06z.=20

DISCUSSION...GOES-W WV suite depicts a weak baroclinc leaf with
transverse banding lifting northeast toward and starting to
intersect with the SW Oregon coast, this is indicative of a
broadening right entrance to the polar jet and short-wave ridging
across northern California. As such, the forward progression of
the front has fully stalled with weak rain-cooled support pressing
the pre-frontal convergence/isentropic band across Sonoma/Santa
Rosa counties at this time. The upstream edge of the divergence
pattern aloft well-offshore is helping to spur a weak surface low
along the front which will help lift the best moisture flux
convergence axis northward after 23-00z with some increased
southerly flow at the coastline, shifting the axis back to
Menodcino county later in the valid time period (03-06z).=20

Recent surface observations have seen dew-points rising through
the San Francisco Bay and filtering into the Sacramento Valley,
suggesting the warm front has over-topped or is near over-topping
the coastal range. CIRA LPW hints at this as well with .5-.75" at
the sfc/850mb layer pressing through the north-central CA coast.=20
LPW also denotes better alignment through depth and so moisture
totals are reaching 1.3" and nearing 1.5" just upstream off-shore.
Total IVT ranges are about 750-900 kg/m/s along and just offshore,
given said moisture and continued solid 50-60kts of fairly
orthogonal 850mb flow in the core of the PW plume. As such,
.5"/hr rates in the coastal range are increasingly probable
supported by 50-75% neighborhood probability along the coastal
range wavering north/south with the passing surface inflection
toward 03z. Totals across the coastal range vary from 2-4.5" and
soils are starting to fully saturate. FFG values along the spine
are about 1.5"/3hrs and given the recent saturation, it is
becoming increasingly plausible of exceedance but probably
probability still remain just below threshold.=20

As mentioned, deeper moisture is filtering through the Sacramento
Valley, though cooler and drier air remains coincident with the
front range, this further intensifies the isentropic ascent plane
increasing verticality of of the showers. Core of the plume still
appears directed at the Butte/W Plumas county slopes, and HREF
probability of 1"/hr reach 15-20% suggesting a spot or two for a
few hours are likely to reach .75"/hr of rainfall, peaking in the
23-01z time frame. Even IVT values are in the 600+ kg/m/s range
supporting this potential.Persistence of southwesterly warm-air
advection will press freezing levels steadily up slope as well,
broadening the area of moderate to heavy rainfall in steeper
terrain. Similar but slightly higher 1.5-2"/3hr FFG values exist
across this area and while there is increased potential for higher
intensity rates, the duration of moderate to heavy rainfall
pre-cursory to this surge has been limited relative to the coast.=20
While a spot or two of FFG exceedance is possible, it will need to
be monitored closely...but will continue to maintain a Heavy
Rainfall tag for this MPD valid time.

Further north toward Cape Mendocino into the SW slopes of the
Trinity Range...
The core of the moisture will continue to be focused south, but
given proximity to the stationary front/triple point, convergence
should be maximized to allow for similar occasional upticks to
.5"/hr. Given this area has the climatologically wetter climate
and higher natural FFG values, the risk for flooding will continue
to be better accommodated than further south. Though and
additional 2-3" rainfall expected; this further saturation will
result in greater run-off further setting the stage for expected
activity over the next coming few days.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9xDAmHd0dfUfszK6USAAuGP2uXiKZFEHFeccEVhVueDyl15euGpcO2pRhLV0bGHSAjo9= jRsvBSK4K2yv0Y6fPc8nx7I$ for graphic product...

ATTN...WFO...EKA...MTR...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON 41782411 41612388 41312362 40982347 40982270=20
41072204 40152159 39422087 38702061 38422091=20
38292172 38102232 37872287 38332328 38832377=20
39622397 40022422 40352452 40642443 41242428=20
41672428=20

=3D =3D =3D
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AWUS01 KWNH 210601
FFGMPD
CAZ000-211800-

Mesoscale Precipitation Discussion 1162
NWS Weather Prediction Center College Park MD
100 AM EST Thu Nov 21 2024

Areas affected...Northern California

Concerning...Heavy rainfall...Flash flooding possible

Valid 210600Z - 211800Z

SUMMARY...Nearly stationary atmospheric river will maintain heavy
rainfall across northern CA through Thursday morning with
increasing concerns for widespread areal flooding and possibly
some burn scar flash flooding.

DISCUSSION...The latest GOES-W Airmass RGB satellite imagery in
conjunction with CIRA-ALPW data shows a well-defined atmospheric
river and an associated front currently stalled over northern CA
and the adjacent offshore waters extending southwestward off the
West Coast. Strong warm air advection and moisture transport
focused in close proximity to this front continues to overrun
northern CA with rather widespread moderate to heavy rain
impacting the region.

Strong low to mid-level southwest flow around the south side of a
powerful deep layer cyclone west of Vancouver Island will be
locked in place overnight and through Thursday morning which will
maintain enhanced atmospheric river activity over northern CA.
Multiple weak waves of low pressure are expected to ride
northeastward along the front over the next 6 to 12 hours which
will take aim on the northern CA coastal ranges, and this will be
facilitated by some backing of the mid to upper-level flow as
additional shortwave/jet energy digs through the base of the
larger scale trough offshore of the West Coast.

Enhanced 850/700 mb moisture flux coupled with the deeper layer
warm air advection pattern and orographic ascent/upslope flow over
the higher terrain of northern CA will focus a persistence of
moderate to heavy rain, with IVT magnitudes north of the Bay Area
reaching 500 to 750+ kg/m/s. This will support elevated rainfall
rates which based off the 00Z HREF guidance should occasionally
reach well into the 0.50" to 0.75"/hour range. Some isolated rates
potentially exceeding 0.75"/hour will be possible and especially
over southern parts of Humboldt County where the southwest-facing
slopes will see stronger orographic ascent coupled with very close
proximity of the aforementioned front.

The persistence of these elevated rainfall rates over the next 6
to 12 hours will likely result in additional rainfall amounts by
18Z (10AM PST) Thursday morning of 3 to 5 inches over the coastal
ranges and the foothills of the northern Sierra Nevada, with some
isolated 6+ inch amounts possible. These rains will be in addition
to the already several inches of rain that have fallen for the
event, and thus isolated some storm total amounts by late Thursday
morning may well be 10+ inches. Lesser amounts of as much as 1 to
3 inches will generally be expected for the interior valleys
including the northern Sacramento Valley.

Expect increasing concerns for widespread areal flooding impacts
from the additional rainfall going through Thursday morning, and
this may include some concerns for burn scar flash flooding at
least locally. Debris flow and landslide activity will be a
notable concern as well from these heavy rains.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9BjNe-FW4HxpKd13oWUWc_JNgylrROGd6XTEv4pWKbm3bvcktYTNiMqJ079UYAML0jex= TIjq5wZE6gguTaoK9-EWBdE$ for graphic product...

ATTN...WFO...EKA...MFR...MTR...STO...

ATTN...RFC...CNRFC...NWRFC...NWC...

LAT...LON 41972347 41602315 41142289 41142210 40672151=20
40082122 39472046 39052031 38842061 38542159=20
38122193 37882259 38322329 39262410 40662456=20
41842417=20

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AWUS01 KWNH 211731
FFGMPD
CAZ000-220400-

Mesoscale Precipitation Discussion 1163
NWS Weather Prediction Center College Park MD
1230 PM EST Thu Nov 21 2024

Areas affected...Northern California...

Concerning...Heavy rainfall...Flash flooding possible

Valid 211730Z - 220400Z

SUMMARY...Remarkably static and intense AR moisture flux
continuing to compound rainfall totals. Spots of add'l 3-6"=20
totals expected through 04z ahead of next enhanced surge
associated with deepening cyclone. Soils are nearly fully
saturated so greater run-off is expected. Flash flooding remains
possible.

DISCUSSION...GOES-W Airmass and RAP analysis shows post-frontal
deep dry air mass with red hues converting quickly to yellows and greenish-blues along and south of the front depicts strength of
the front and ability to increase thermal wind along and south of
the boundary though a large depth of the atmosphere. This
unidirectional flow through depth is expected to remain though the
next 9 to 12 hours directed at the Redwood Coastline and
continuing to infiltrate well into northern California and the
northern Sierra Nevada and Trinity Ranges...continuing similar
evolution to unfold.

This will be changing into the 03-06z period...GOES-W WV suite
denotes a short-wave rounding the base of the global trough just
east of 40N140W, which will be spurring rapid cyclogenesis over
the next 12-24hrs. This will strengthen and amplify the flow
nearing the coast, but that is for subsequent MPD issuance. Its
influence, however, is starting to be felt in other downstream
fields; including upper-level jet starting to split/ridge a bit
across coastal OR and peripherally N CA. This will provide broad
right entrance ascent from the exiting jet streak across the
region and a very weak surface wave(s) are noted near Cape
Mendocino into SW OR; low level winds appear to be responding with
slightly backed flow especially along and east of the coastal
range, further enhancing deep moisture flux through the northern
Sacramento Valley and increasing orographic ascent (while further
increasing freezing levels above nearly all peaks minus Shasta by
the end of the valid time).=20=20

CIRA LPW analysis shows a small split in the low level moisture
further upstream, likely associated with the approaching shortwave DPVA/cyclogenesis. This enhanced area however, has solid
isentropic slope through the 700-500mb layer that is currently
intersecting far NW CA and overlaid with the leading surface to
850 (and 850-700mb) slug of moisture from Cape Gorda through the
San Francisco Bay (and up through the Sacramento Valley). This is
resulting in solid core of 1.25-1.5" with embedded spots just over
1.5". The strength of the moisture flux in the sfc-850mb (about
.6-.75") on steady 45-50kt winds is solidly within the 95-99th
percentile of CIRA LPW moisture flux values. This matches with
consistent and remarkably broad 600 kg/m/s ticking up to 700
kg/m/s in the core directed at S Mendocino/N Sonoma county. This
will result in consistent .33"/hr rates with occasional .5"+/hr
spurts in the southwest facing topography of the Coastal Range.=20
Spots of additional 3-6" totals are expected and given 6-12" that
have fallen in spots, soil saturation has reached 90% with spots
over that. This will result in increased run-off and may spur
mudslides and debris flows, especially in/near recent burn scars.=20
As such, will continue to tag this MPD as flash flooding
possible...though it remains more the duration of the rate that is
driving the flooding conditions.

A bit less consistent with a slow northward intersection with the
northern Sierra Nevada Range of 500-600 kg/m/s, but slightly
increased moisture flux convergence due to cyclonic acceleration
through the gap of the Bay, should see similar rates and totals in
strongest orographic ascent (Butte/Plumas county). OAK 12z RAOB
showed near daily record of 1.25" TPW and that continues to
increase with approaching core of moisture through the gap to
indicate how anomalous the deep moisture is within the central
valley. Slow sfc to 850mb backing of the flow will redirect
orientation of the plume toward the eastern Trinity Range toward
00z, reducing orthogonal flow into the Sierra Range. Still,
swaths of 3-5" from Butte to Tehama and 2-3" into Shasta county
are expected.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!47mgUUzyezbC5IOK_B6T_CgFjJXAY9hExwobLZoQgLdiY8DG_zBvSSJ8WaUpY1aUJWJN= pe2rEFldNv6fk3tbi2uKR5w$ for graphic product...

ATTN...WFO...EKA...MFR...MTR...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON 41582391 41562347 41322293 41382250 41362231=20
41262177 40722153 40212113 39462076 39072106=20
39122139 39462177 39692222 39332243 38902229=20
38412237 38212291 38522340 38822370 39272392=20
39742400 40212441 40592447 41092422=20

=3D =3D =3D
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AWUS01 KWNH 220401
FFGMPD
CAZ000-ORZ000-221600-

Mesoscale Precipitation Discussion 1164
NWS Weather Prediction Center College Park MD
1100 PM EST Thu Nov 21 2024

Areas affected...Northern California...Southwest Oregon

Concerning...Heavy rainfall...Flash flooding possible

Valid 220400Z - 221600Z

SUMMARY...Strong atmospheric river activity will continue to
impact areas of northern CA overnight and into early Friday while
gradually refocusing farther north back into portions of southwest
OR. Widespread areal flooding concerns will continue, and there
will also still be a possibility for some localized burn scar
flash flooding impacts.

DISCUSSION...The latest GOES-W GeoColor satellite imagery is
showing the rapid deepening of a new area of low pressure offshore
of the West Coast as strong shortwave energy rounds the base of
the persistent larger scale upper-level trough. This low pressure
center will strengthen over the next 6 to 12 hours and move to a
position southwest of Vancouver Island by later Friday morning. As
this occurs, the long duration, multi-day atmospheric river that
continues to impact northern CA will advance a bit farther north
and edge back into areas of southwest OR which will be the result
of a backing of the deeper layer flow across the region and the
northward advance of a warm front. By very early Friday morning, a
cold front will then begin to arrive across coastal areas of
southwest OR and northwest CA.

Enhanced low to mid-level southwest flow out ahead of this cold
front will continue to drive areas of persistently heavy rain
given the level of moisture transport and warm air advection
coupled with upslope flow/orographic ascent over the higher
terrain. The 850/700 mb moisture flux anomalies are forecast to
peak between 3 and 5 standard deviations above normal by around
12Z (4AM PST) across coastal areas of northwest CA and southwest
OR and the IVT magnitudes are forecast to locally peak in between
750 and 1000 kg/m/s. While the highest values of IVT will be along
the immediate coast, some of these elevated IVT magnitudes are
forecast to spread inland including the northern Sacramento Valley.

The 00Z HREF guidance suggests rainfall rates will occasionally
reach 0.50" to 0.75"/hour, with potentially some spotty rates in
the 0.75" to 1.0"/hour late tonight as peak IVT magnitudes arrive
ahead of the cold front. Additional rainfall totals going through
early Friday morning are expected to reach 3 to 5 inches, with
isolated heavier amounts not out of the question. Given the
persistence of the rainfall, and level of soil saturation and high
streamflows already from this multi-day atmospheric river event,
there will continue to be concerns for widespread flooding going
through Friday morning. This may again include concerns for some
burn scar flash flooding impacts at least locally.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4amqt4Yia4ywGGBmpYQ5syqEWjlez0Y0p1eEDtF4ZeILjefM_XxtmjRYS7L5njN9j6-o= R0agJvqPCaATEVyykVr1LXU$ for graphic product...

ATTN...WFO...EKA...MFR...MTR...REV...STO...

ATTN...RFC...CNRFC...NWRFC...NWC...

LAT...LON 43542413 43432352 42482323 41812272 41672224=20
41692162 41402136 40982140 40402082 39812057=20
39322086 38962179 38232215 38022260 38282320=20
39062390 39812426 40672459 42002459 43102467=20 =20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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AWUS01 KWNH 221645
FFGMPD
CAZ000-230400-

Mesoscale Precipitation Discussion 1165
NWS Weather Prediction Center College Park MD
1144 AM EST Fri Nov 22 2024

Areas affected...cenral to northern CA

Concerning...Heavy rainfall...Flash flooding possible

Valid 221643Z - 230400Z

SUMMARY...The atmospheric river will continue to gradually shift
southward across north-central CA today and early tonight. While
the magnitude of moisture flux will be lower than earlier today,
locally significant impacts will remain possible where areas of
training allow rainfall rates in excess of 0.5 in/hr. Additional
rainfall through 04Z of 3 to 7 inches for the northern Sierra
Nevada and localized totals of 2-4 inches for the Coastal Ranges
are anticipated.

DISCUSSION...16Z surface observations showed that a northward
moving surface low continued to deepen roughly 250 miles west of
the northern OR coast, with an attached occluded/cold front now
inland across northern CA. GOES West water vapor imagery showed
the strengthening mid to upper-level reflection of this surface
low with the associated upper low moving inland across the Pacific
Northwest. IVT values have weakened from near 1000 kg/m/s earlier
this morning near the coastal OR/CA border but remained of a
moderate intensity in the 600-700 kg/m/s range per short term
model forecast data. While the intensity of the atmospheric river
has decreased, there are indications upstream in water vapor
imagery that short periods of stalling may occur with the moisture
axis, along with a temporary increase in IVT values later this
afternoon and early evening. While subtle inflections were noted
in water vapor imagery within the southwesterly flow pointed at
CA, which could allow for brief training, a more notable shortwave
impulse was observed near 35N 140W which could result in a longer
period of training potential.

As this mid-level shortwave impulse near 140W continues to advance
toward the east, RAP guidance indicates some amplification within
the base of the broader parent closed low and slowing/stalling of
mid-upper level height falls across the central CA coast. At the
surface, a weak surface wave along the cold front is forecast to
develop and approach the CA coast which will result in some minor
increase in IVT values (up to 800 kg/m/s) and slowing/stalling of
the plume over the San Francisco metro region with 850 mb winds
intensifying to near 60 kt along the coast. The best indication
for stalling will be in the 21Z-03Z time frame.

Downstream across the Great Valley into the Sierra Nevada, 700 mb
winds up to ~70 kt are expected later today with upslope
enhancement favoring the greatest likelihood of 0.5 to 1.0 inch of
rain in an hour or less. Additional rainfall totals through 04Z of
3-7 inches are expected for the Sierra Nevada along with localized
2-4 inch totals for the Coastal Ranges. Urban flooding impacts
will be possible as well given overlap with the San Francisco and
Sacramento metro regions and the addition of 1 to 2 inches, though
rates are likely to remain below 0.5 in/hr outside of terrain due
to negligible forecast instability.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9M6z_0wuTofaY4LB0_ojO6STfSKvkNKxKeGkkE-nBG6bfN1s7925Pl2uPNa2e32fHeem= CATXbgPjIVTW2hAz_zYK13M$ for graphic product...

ATTN...WFO...EKA...MFR...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON 41662174 41602146 41102119 40502072 39572017=20
39262006 38712026 38232078 37692133 37022163=20
36822200 37132258 37822319 38812384 39602360=20
40532302 41182266 41562216=20

=3D =3D =3D
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AWUS01 KWNH 230417
FFGMPD
CAZ000-231500-

Mesoscale Precipitation Discussion 1166
NWS Weather Prediction Center College Park MD
1115 PM EST Fri Nov 22 2024

Areas affected...Portions of Central and Northern CA

Concerning...Heavy rainfall...Flash flooding possible

Valid 230415Z - 231500Z

SUMMARY...Strong multi-day atmospheric river event gradually
beginning to wane across central and northern CA, but flooding
concerns will continue into Saturday morning.

DISCUSSION...The long duration, multi-day atmospheric river
impacting central and northern CA is generally past peak at this
point and will be weakening in intensity going through Saturday
morning. However, there will continue to be sufficient levels of
additional rainfall for additional flooding concerns overnight.

GOES-W Airmass RGB satellite imagery along with CIRA-ALPW data
shows the atmospheric river axis along with an associated frontal
boundary aligned in a southwest to northeast fashion across the
Bay Area and extending inland across the Central Valley and the
adjacent windward slopes of the central and northern Sierra
Nevada. A wave of low pressure is noted riding northeast along the
front, and this coupled with stronger upper-level jet
dynamics/forcing advancing inland is still maintaining a corridor
of stronger IVT magnitudes and thus some enhanced rainfall rates.

IVT magnitudes are currently on the order of 700 to 800 kg/m/s
just south of the Bay Area and are in between 500 and 700 kg/m/s
across the Central Valley. Rainfall rates associated with this are
still reaching upwards of 0.50" to 0.75"/hour on occasion across
the coastal ranges and into the some of the orographically favored
upslope areas of the Sierra Nevada. As the cold front gradually
advances east and inland across the region, the high 850/700 mb
moisture flux anomalies and related IVT magnitudes will begin to
weaken, and this will eventually allow the rainfall rates to
subside.

The 00Z HREF guidance maintains high probabilities though of
seeing 0.50"+/hour rainfall rates going through about 09Z (1AM
PST) down across Santa Cruz, Santa Clara and Monterey Counties
before subsiding. Farther inland, with the enhanced IVT magnitudes
and upslope flow just ahead of the front still impacting the
foothills of the Sierra Nevada, these 0.50"+/hour rainfall rates
should persist through 12Z (4AM PST) across these areas and
including Butte and Yuba Counties southward down through Tuoloumne
and Mariposa Counties.

Locally an additional 2 to 4 inches of rain will be possible with
locally heavier amounts, and these additional rains are expected
to maintain areal concerns for flooding going into early Saturday
morning before the rainfall rates taper down. Some additional
debris flows, rock and landslide activity, and perhaps an isolated
concern for burn scar flash flooding will be possible overnight.
Conditions should improve substantially Saturday morning as the
front passes through the region and the atmospheric river impacts
gradually come to an end.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4fKb18QgT9BSU13-3IlGEnq8f5EFxNcKGJOLaeIfbgoYxUkvXDF1YnL67zR2_J6CELQi= sThJk5SihYatPr-S-Qz3KDY$ for graphic product...

ATTN...WFO...HNX...LOX...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON 40912135 40612096 40162058 39262043 38181971=20
37651919 37031889 36661921 36302017 35812051=20
35502107 35862167 36482218 37332260 38212285=20
39342226 40452191 40832163=20

=3D =3D =3D
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