ACUS48 KWNS 260854
SWOD48
SPC AC 260852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Thu Jun 26 2025

Valid 291200Z - 041200Z

...DISCUSSION...
On the large scale, a low-amplitude upper trough over the northern
Plains on Sunday/D4 will amplify as it moves toward the upper Great
Lakes into Monday/D5, and more so into Tuesday/D6 when it will
stretch across into the Northeast.

At the surface, high pressure will extend into the northern to
central Plains on Sunday/D4, with a trough affecting the upper MS
Valley to central Plains. This trough/front will push farther south
on Monday/D5, extending roughly from the OH Valley into the southern
Plains, and eventually, into the Gulf Coast states into Wednesday/D7
as high pressure spreads into the MS Valley.

For the period, instability looks to be strongest on Sunday/D4 ahead
of the front from NE/KS into IA/MO/IL with upper 60s to lower 70s F
dewpoints common. While unstable, only weak westerly flow aloft will
be present, and this will likely result in south to southwest
propagating cluster of storms producing areas of gusty winds. Given
substantial storm coverage over much of the central Plains to
upper/middle MS Valley, predictability remains low for denoting
precise risk areas.

A low-end risk of severe storms with wind potential could develop
into the Mid Atlantic on Tuesday/D6 as the Great Lakes/Northeast
trough amplifies with westerlies increasing to 30 to perhaps 40 kt
at 500 mb. Otherwise, scattered storms will also occur away from
this boundary, across much of the Southeast as the moisture and
instability remain in place in a weak shear environment.

..Jewell.. 06/26/2025

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ACUS48 KWNS 270856
SWOD48
SPC AC 270855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Fri Jun 27 2025

Valid 301200Z - 051200Z

...DISCUSSION...
A mid-level trough will amplify across the Great Lakes at the
beginning of the period D4/Monday and shift into the Northeast by
Tuesday. A surface cold front will shift east across the Great Lakes
on Monday and to the Northeast and Mid-Atlantic on Tuesday. Moderate instability may develop across a large area east of the Appalachians
on Day 5/Tuesday. The strongest shear is forecast from Pennsylvania
northward, beneath the strongest mid-level flow. However, the
greatest instability should remain mostly south of this better flow.
Therefore, a favorable corridor may develop for some strong to
severe storms near the Mid-Atlantic/Carolinas where instability and
modest shear overlap, but this remains too uncertain for severe
weather probabilities at this time.

Beyond Day 5, mid-level ridging will shift east across the central
CONUS. At the surface, high pressure will build across much of the
eastern CONUS. The combination of weak mid-level flow beneath the
mid-level ridge and surface high pressure should limit severe
weather potential for Day 6 and beyond. Strong instability is
forecast to return to the northern Plains, but given the lack of
mid-level flow, any storms will likely only be marginally severe at
best. Some stronger mid-level flow may return to the northern Plains
by next weekend as the ridge starts to break down, which may be the
next chance for more organized severe storms in the latter portion
of the extended period.

..Bentley.. 06/27/2025

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ACUS48 KWNS 280801
SWOD48
SPC AC 280800

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CDT Sat Jun 28 2025

Valid 011200Z - 061200Z

...DISCUSSION...
A mid-level trough will move from the Great Lakes to the Northeast
on Day 4/Tuesday. At the surface, a cold front will move east
through the period. Moderate instability is expected along this
front and some severe weather may be possible from the Mid-Atlantic
to the Northeast. Slight risk (15%) probabilities may eventually be
needed within this zone, but there is potential for
cloudcover/thunderstorm activity from Monday evening to impact
destabilization. Therefore, confidence is not high enough for
probabilities at this time.

Beyond Day 4, a relative lull in severe weather potential is
expected. Multiple reinforcing mid-level troughs will amplify the
larger-scale trough across the eastern CONUS. As this occurs, the
surface cold front will move south, potentially to the Gulf Coast
and into the western Atlantic. This will eliminate the very moist
airmass which resulted in moderate to strong instability across much
of the eastern CONUS for the past few weeks.

The greater low-level moisture is expected to remain and perhaps
advect north across the central Plains beneath a large-scale ridge.
This could result in some thunderstorm activity, but shear is
expected to be very weak, and the building ridge aloft may suppress
convection on D5/Wednesday to D6/Thursday.

By next weekend, this ridge is expected to flatten with some
stronger mid-level flow moving across the northern Plains. The exact
evolution of the upper-pattern remains uncertain and therefore,
confidence is low, but severe weather chances may increase across
the northern Plains by next weekend.

..Bentley.. 06/28/2025

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ACUS48 KWNS 290820
SWOD48
SPC AC 290819

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0319 AM CDT Sun Jun 29 2025

Valid 021200Z - 071200Z

...DISCUSSION...
The cold front which may result in severe weather on Day 3/Tuesday
will move into the Atlantic and near the Gulf Coast across Florida.
A reinforcing mid-level trough will maintain northerly flow across
the eastern CONUS as an area of high pressure builds into the
region. A drier, more continental airmass across the eastern CONUS
will keep severe weather chances minimal.

Upper 60s to low 70s dewpoints will remain across the Plains,
beneath a strong upper-level ridge. By the time the ridge starts to
break down on Day 6/Friday some severe weather is possible as a
mid-level trough moves into the northern Plains. However, the ECMWF
shows less than 20 knots of flow across the Plains. Therefore, shear
will likely be limited. Thunderstorms will be likely along the cold
front as it traverses the central and eastern CONUS next weekend.
However, the lack of stronger mid-level flow casts doubt on storm
organization. Therefore, no severe weather probabilities have been
added at this time.

..Bentley.. 06/29/2025

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ACUS48 KWNS 300855
SWOD48
SPC AC 300853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Mon Jun 30 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A mid-level ridge will start the extended period across the Plains
on D4/Thursday. This ridge will shift east through the extended
period. A surface low will develop in the lee of the Rockies and
move slowly north and east, reaching eastern Ontario by D7/Sunday.
This surface low and its associated cold front will likely be the
only potential for any severe weather during the extended period.
However, at this time it appears the stronger shear will be well
displaced from the greater instability. Therefore, severe weather
probabilities are not necessary at this time.

Outside of this frontal zone during the Day 4 to Day 7 period,
thunderstorms are likely. However, weak lapse rates and very weak
shear is anticipated, with minimal storm organization.

..Bentley.. 06/30/2025

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ACUS48 KWNS 010902
SWOD48
SPC AC 010900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Tue Jul 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
A mid-level trough will traverse the Northern Plains and Upper
Midwest on Friday. This will likely be the most substantial severe
weather threat during the extended period before broad, strong
ridging builds across much of the eastern/central CONUS.

...Day 4/Friday...
As a positively tilted mid-level trough traverses the northern
Plains on Friday, strong southerly flow will advect moisture
northward across a broad warm sector near the Upper Midwest. This
will result in moderate to strong instability as temperatures warm
well into the 80s. Widespread thunderstorms are likely along the
frontal zone during the afternoon/evening. 35 to 40 knots of
mid-level flow will overspread the warm sector which will provide
some shear for storm organization. However, southwesterly surface
winds will also increase during the afternoon within the warm front
and therefore, the net shear may remain somewhat minimal. Some
organized storms with a threat for large hail and severe wind gusts
are possible, but the aforementioned concerns about deep-layer shear
preclude the confidence needed for 15% severe weather probabilities
at this time.

Beyond Day 4, moderate to strong instability is forecast across much
of the central and eastern CONUS with widespread thunderstorm
activity likely. However, shear will remain mostly nebulous with the
stronger mid-level flow confined to areas north of the better
instability. Therefore, some marginal regional severe weather threat
will be likely most days, but a more organized severe weather risk
appears unlikely at this time.

..Bentley.. 07/01/2025

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ACUS48 KWNS 020859
SWOD48
SPC AC 020857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Wed Jul 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Some severe weather is possible on Day 5/Sunday and Day6/Monday
across portions of northern Montana and North Dakota as moderate
instability builds into the area with moderate mid-level flow
southeast of a trough across western Canada. The evolution and
timing of this trough remains uncertain and therefore, no severe
weather probabilities will be added at this time.

Beyond this timeframe, moderate to strong instability is forecast
across much of the central and eastern CONUS for much of the
extended forecast period with widespread thunderstorm activity
likely. Despite this storm coverage and instability, organized
severe weather seems unlikely given mostly weak deep-layer
shear/flow.

..Bentley.. 07/02/2025

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ACUS48 KWNS 030859
SWOD48
SPC AC 030858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Jul 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
During the extended forecast period, a mid-level ridge will build
across the InterMountain West. Aside from the primary ridge, there
will be several mid-level shortwave troughs throughout the flow
across the Northwest and also from the Great Lakes to the Atlantic
coast. Widespread thunderstorm activity is expected throughout the
period, but stronger mid-level flow/shear should mostly stay north
of the stronger instability early in the period.

At some point next week (mid week according to the GFS and late next
week into the weekend ECMWF) mid-level northwesterly flow will
likely strengthen across the Plains (to the east of the primary
ridge). Whenever this occurs, the pattern would favor severe MCSs
given the forecast strong instability and moderate deep-layer shear.
However, the uncertainty in the upper-level pattern remains too
great to provide an accurate forecast of the timing and location of
the greatest severe weather threat toward the middle to late part of
next week.

..Bentley.. 07/03/2025

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ACUS48 KWNS 040842
SWOD48
SPC AC 040841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Fri Jul 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
An upper ridge will gradually build over the Southwest while mainly
zonal mid-level flow persists over the northern CONUS through next
week. A relatively nebulous surface pattern will be the norm through
the extended range. Rich low-level moisture will overspread the
CONUS east of the Rockies Days 4-8/next Monday-Friday, supporting
scattered thunderstorm development over much of the Great Plains
into the MS Valley, and the Southeast into the Northeast. The best
chance for at least isolated strong to potentially severe storms in
the upcoming week would be across the north-central CONUS. Here, the
low-level moisture will advect northward beneath relatively cooler
temperatures and modest northwesterly flow/shear aloft. However,
given the nebulous and weakly forced environment, confidence is too
low to delineate severe probabilities over the north-central U.S.
for any given day.

..Squitieri.. 07/04/2025

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ACUS48 KWNS 050848
SWOD48
SPC AC 050846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Sat Jul 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
An upper ridge will build across the Southwest and remain in place
this upcoming week into next weekend. Relatively zonal mid-level
flow will persist over the northern CONUS through the extended
forecast period, with multiple embedded impulses expected to track
eastward within the zonal flow. As the mid-level impulses traverse
the northern Plains, isolated strong to severe storm development
will be possible given the presence of ample buoyancy. However,
there are appreciable differences in the placement and timing of
these impulses among medium-range guidance members. Therefore,
severe probabilities have been withheld since confidence is
currently low regarding where and when organized clusters of severe
storms will develop.

..Squitieri.. 07/05/2025

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ACUS48 KWNS 060830
SWOD48
SPC AC 060829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Sun Jul 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
An upper ridge will remain in place across the Southwest while zonal
mid-level flow continues to support embedded impulses traversing the
northern CONUS this week into next weekend. The first notable
mid-level impulse, which will bring severe potential to the central
U.S. in the Days 2-3 time-frame, will approach the East Coast while
slowing its forward advance. The impulse should reach the East Coast
by Day 4 (Wednesday), providing adequate lift for at least scattered thunderstorms through the remainder of the week. Given preceding
rich low-level moisture, ample buoyancy will be available to support
at least isolated strong storms with potentially damaging gusts.

A more pronounced mid-level trough will approach the Northern Plains
in the Days 4-5 (Wednesday-Thursday) period, resulting in strong
surface troughing and the northward advection of rich low-level
moisture. Medium range guidance consensus shows that strong
instability will precede the upper/surface troughs, favoring the
development of severe storms. The first chance for severe storms
will be over the western Dakotas on Wednesday as the upper trough
approaches from the Northern Rockies. Upper support in this region
does not currently appear robust, so severe storms may occur on a
more isolated basis (hence no severe probabilities introduced at
this time). However, there is medium range guidance agreement in the
upper trough ejecting into the northern Plains on Day 5 (Thursday),
with some guidance suggesting that instability could become extreme.
Though it is difficult to confidently pinpoint storm mode this far
in advance, guidance hints at the development of a persistent,
elongated convective system, which may be capable of supporting all
severe hazards, especially severe winds. Severe probabilities have
been added to address this scenario.

As the pronounced mid-level trough progresses eastward, more
organized severe storms are possible over the MS Valley and perhaps
points east Day 6 onward. However, the intensity, coverage, and
location of severe potential will be highly dependent on the
evolution of convection from previous days, which is hard to know
this far in advance. Therefore, severe probabilities have been
withheld this outlook.

..Squitieri.. 07/06/2025

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