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  • HVYSNOW: Probabilistic Heavy Snow And Icing Discussion

    From COD Weather Processor @1:2320/107 to All on Sun Oct 11 07:05:28 2026
    FOUS11 KWBC 110705
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    305 AM EDT Sun Oct 11 2026

    Valid 12Z Sun Oct 11 2026 - 12Z Wed Oct 14 2026

    ...Northern Rockies...
    Day 1...

    Banded snow will continue through the day today over western
    Montana into the high terrain of western Wyoming as the upper low
    over WA/OR slowly sinks southward and narrows. This will maintain
    SW flow over the Northern Rockies and eventually help to bring
    northward the remnant moisture of Rachel by this evening/overnight.
    Snow rates of about 0.5"/hr will continue through the day but
    increase later tonight over MT with the additional moisture surge
    when 1"/hr rates will again be possible after Saturday's initial
    snowfall. By Monday morning, heights will rise slightly over the
    region as the upper low digs farther into CA/NV, largely ending the
    snow over the region.

    WPC probabilities for an additional 6 inches of snow are >80%
    along the eastern slopes of the Lewis and Flathead Ranges then east
    over the Belts, and 50-70% in the adjacent terrain down to around
    3800ft MSL.

    Into WY, higher snow levels will limit accumulations to the high
    Wind River Range and Absarokas where an additional 1-2ft of snow is
    likely.


    ...Sierra Nevada/Great Basin Ranges/Utah Ranges/Southwest CO...
    Days 1-3...

    The upper low over OR will sink southward today and dig into CA/NV
    as the remnant Rachel moisture zips northeastward. Light snow is
    expected for only the highest peaks. By Monday, as heights start to
    fall, snow levels will drop to 6000ft as moisture increases over
    the Sierra and especially across the Great Basin to Utah. As the
    upper low turns eastward across NV into UT, snow will spread
    eastward into western CO but with high snow levels around 11,000ft.
    Still, the combination of height falls, abundant moisture, and
    orographic upslope will yield modest snow for the high terrain
    through early Wednesday. The Unitas may see 1-2ft with at least 8
    inches likely (>70% chance) above 9000ft or so across NV and
    10,000ft across central/southern UT. Light snow will overspread the
    San Juans in SW CO Tuesday and continue through the end of the
    period with >50% chance of at least 4 inches above 11,000ft.

    The probability of significant ice across the CONUS Days 1-3 is
    less than ten percent.


    Fracasso


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  • From COD Weather Processor @1:2320/107 to All on Sun Oct 11 20:28:32 2026
    FOUS11 KWBC 112028
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    428 PM EDT Sun Oct 11 2026

    Valid 00Z Mon Oct 12 2026 - 00Z Thu Oct 15 2026

    ...Montana...
    Day 1...

    Remnant energy and moisture from Rachel will lift northeast from
    northern Utah through western Wyoming this evening and then across
    east-central MT overnight. Associated broad precip shield lifts
    north from eastern Idaho rest of the afternoon. Areas north of the
    stationary front over far northwest Wyoming can expect more snow
    with local enhancement from banding. Snow rates of 0.5 to 1" per
    hour can be expected across much of west-central Montana through
    this evening. Rates up to 0.5" per hour cross north-central Montana
    overnight. Day 1 snow probs for >4" are 40-80% across much of
    west-central and southwest Montana and 20-50% in terrain around
    the Fort Belknap Reservation. Snow should be largely northeast of
    Montana by 12Z Monday.


    ...Intermountain West Terrain...
    Days 1-2...

    The mid-level low over Oregon will drift south across Nevada
    through Tuesday before swinging east to the Four Corners through
    Wednesday. Robust warmth and moisture to the east over the
    Intermountain West will keep snow levels around 10,000ft from
    Nevada through Wyoming tonight with height falls bringing the level
    down to around 7000ft over central Nevada Monday. The eastward
    progression of some cooler air continues with Utah snow levels
    dropping to around 8000ft Monday night while only dropping to
    9000ft over Wyoming. Day 1 and 2 snow probs for >6" are 30-60%
    over central NV and southern UT and Wasatch ranges and 50-80% for
    the high Uinta and Wind River ranges.


    ...Colorado Rockies...
    Day 3...

    The low over the Four Corners Wednesday brings snow levels over the
    CO Rockies to around 9000ft. Light to moderate precip rates allow
    Day 3 snow probs for >6" to be 30-60% for the Front Range, central
    CO ranges, and the highest San Juans.


    ...Northern and Western Maine...
    Day 2...

    A progressive low tracks east from the eastern Great Lakes Tuesday
    with leading warm air advection leading to a wintry mix over
    interior Northern Maine. If there is enough of an inversion, then
    snow, sleet, and even some freezing rain are likely. Day 2 snow
    probs for >4" are around 10% in northern Aroostook Co. A bias to
    freezing rain in many ptype algorithms may be pointing to far in
    that direction, but for now Day 2 ice probs for >0.1" are up to
    around 10% in western interior Maine near the Quebec border.


    Jackson


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  • From COD Weather Processor @1:2320/107 to All on Mon Oct 12 07:50:56 2026
    FOUS11 KWBC 120744
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    344 AM EDT Mon Oct 12 2026

    Valid 12Z Mon Oct 12 2026 - 12Z Thu Oct 15 2026


    ...Great Basin to the Central Rockies...
    Days 1-3...

    The mid-level low over eastern Oregon this morning will sink
    southward into Nevada today and head toward the AZ/UT border by
    late Tuesday and into west central Colorado by early Wednesday.
    Snow levels will be rather high ahead of the trough with the
    southwesterly flow into the region. As the upper low moves through,
    snow levels will drop from 9000-11,000ft to about 7000-9000ft
    beneath the upper low itself. Snow will slowly end from west to
    east starting Wednesday afternoon in Nevada and into Utah by the
    end of this forecast (12Z Thu), with snow still ongoing over
    Colorado beneath the upper low. WPC probabilities of at least 8
    inches of snow are >50% above about 7000ft in NV, 9000ft in UT,
    10,000ft in WY, and 11,000ft in CO.


    ...Northern and Western Maine...
    Day 2...

    A cold front will push through Maine tonight into early Tuesday,
    allowing temperatures to fall just below freezing near the Canadian
    border. Surface low pressure over the Great Lakes will ride along
    the front and bring in light to modest precipitation starting
    Tuesday morning. With 750-850mb temperatures just above 0C, some
    sleet or freezing rain is possible for especially sheltered
    locations. The HREF show higher and more expansive probabilities of
    ZR compared to the REFS, but it is the opposite for sleet. Either
    way, a wintry mix is likely for far northwestern/interior Maine
    early Tuesday before milder air turns everything to rain later in
    the day. WPC probabilities of at least 0.1" icing are 10-20% near
    the NH and Canadian borders.


    Fracasso


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  • From COD Weather Processor @1:2320/107 to All on Mon Oct 12 18:21:58 2026
    FOUS11 KWBC 121821
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    221 PM EDT Mon Oct 12 2026

    Valid 00Z Tue Oct 13 2026 - 00Z Fri Oct 16 2026


    ...Great Basin to the Central Rockies...
    Days 1-3...

    The mid-level low over eastern Oregon today will sink southward
    into Nevada tonight, head toward the AZ/UT border by late Tuesday
    and into Colorado by later Wednesday. This system will bring higher
    elevation snow to portions of NV/UT/CO/WY through early Thursday.
    Snow levels will start high, but gradually lower as the upper low
    moves overhead. Nonetheless, any significant snowfall accumulations
    are expected to remain in the elevated terrain. Accumulations of
    at least 8 inches should stay above 9000 feet in Utah and 10000
    feet in CO, with some lighter accumulations potentially getting
    down to 7000 or 8000 feet as the upper low moves overhead. The main
    trend from continuity was an uptick in snowfall accumulations
    above 10000 feet in the San Juan mountains of southwest CO.

    ...Northern and Western Maine...
    Day 1-2...

    A wintry mix is expected to impact portions of western and northern
    Maine Tuesday. Colder air in the low levels and a modest warm nose
    aloft should support some light sleet and/or freezing rain
    accumulations over western Maine Tuesday morning, as highlighted by NBM/HREF/REFS probabilities. Temperatures will be right around
    freezing, and thus only expecting light accumulation of any mixed
    winter weather. Over northern Maine cooler temperatures aloft will
    allow for a period of snow, with the model consensus supporting a
    coating to 2 inches of accumulation.

    Chenard





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  • From COD Weather Processor @1:2320/107 to All on Tue Oct 13 06:37:06 2026
    FOUS11 KWBC 130636
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    236 AM EDT Tue Oct 13 2026

    Valid 12Z Tue Oct 13 2026 - 12Z Fri Oct 16 2026

    ...Northern and Western Maine...
    Day 1...

    A cold front across central New England has allowed temperatures
    over northwestern Maine to fall into the mid 30s with dew points in
    the low to mid 30s. Temperatures aloft remain above 0C (KMWN
    around 4C). WAA-driven precipitation was advancing from the west,
    which could result in a wintry mix of sleet and freezing rain in
    especially colder/sheltered areas this morning, with light snow
    (0.5-1.5") over northern Maine and at higher elevations. Any
    glazing of ice would be light, with low probabilities (<20%) of at
    least 0.1" icing.


    ...Great Basin to the Central Rockies...
    Days 1-3...

    The mid-level low over Nevada will push toward the AZ/UT border by
    late tonight and into Colorado by later Wednesday, finally
    reaching the central Plains by Thursday and weakening. This system
    will bring higher elevation snow to portions of NV/UT/CO/WY, ending
    from west to east and lastly over the CO Rockies Thursday evening.
    Snow levels will start high ahead of the system (8000-10,000ft),
    but gradually lower as the upper low moves overhead (6500-9000ft).
    Any significant snowfall accumulations are expected to remain in
    the elevated terrain, where WPC probabilities for at least an
    additional 8 inches of snow are >50% above 9000-10,000ft in Utah
    and 10,000ft in Colorado. Some lighter accumulations could fall as
    low as 7000 or 8000 feet as the upper low moves overhead. The
    highest amounts will be in the San Juan mountains of southwest CO
    and also across the Medicine Bow and Mosquito Range where over a
    foot is possible.


    Fracasso


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  • From COD Weather Processor @1:2320/107 to All on Tue Oct 13 18:17:52 2026
    FOUS11 KWBC 131817
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    217 PM EDT Tue Oct 13 2026

    Valid 00Z Wed Oct 14 2026 - 00Z Sat Oct 17 2026

    ...Great Basin to the Central Rockies...
    Days 1-2...

    The mid-level low over Nevada will push toward the AZ/UT border by
    late tonight and into Colorado by later Wednesday, finally
    reaching the central Plains by Thursday and weakening. This system
    will bring higher elevation snow to portions of UT/CO/WY, ending
    from west to east and lastly over the CO Rockies Thursday evening.
    Snow levels will start high ahead of the system (8000-10,000ft),
    but gradually lower as the upper low moves overhead (6500-9000ft).
    Any significant snowfall accumulations are expected to remain in
    the elevated terrain, where WPC probabilities for at least an
    additional 8 inches of snow are >50% above 10,000ft in UT and CO.
    Some lighter accumulations could fall as low as 6500 or 7000 feet
    as the upper low moves overhead in southeast WY early Thursday. The
    highest additional amounts will be in the San Juan mountains of
    southwest CO and also across the Medicine Bow and Mosquito Range
    where over a foot is possible.


    Fracasso/Snell





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  • From COD Weather Processor @1:2320/107 to All on Wed Oct 14 06:49:32 2026
    FOUS11 KWBC 140649
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    249 AM EDT Wed Oct 14 2026

    Valid 12Z Wed Oct 14 2026 - 12Z Sat Oct 17 2026

    ...Central Rockies...
    Days 1-2...

    The mid-level low near the Four Corners will move into Colorado
    later this afternoon and weaken as it reaches the central Plains by
    Thursday. This system will bring higher elevation snow to portions
    of UT/CO/WY over the next 36hrs, ending from west to east over
    Utah tonight and lastly over the CO Rockies tomorrow evening. Snow
    levels ahead of the system are high (8000-10,000ft), but will
    gradually lower as the upper low moves overhead to about
    6500-9000ft from UT to CO. Any significant snowfall accumulations
    are expected to remain in the elevated terrain, though this does
    include high passes like I-70/Eisenhower Tunnel at just over
    11,000ft and Vail Pass at 10,666ft. WPC probabilities for at least
    an additional 8 inches of snow are >50% above 10,000ft in UT and
    CO. Some lighter accumulations could fall as low as 6000 or 7000
    feet as the upper low moves overhead in southeast WY early
    Thursday. The highest additional amounts will be in the San Juan
    mountains of southwest CO and also across the Medicine Bow and
    Mosquito Range where over a foot is possible.


    For days 1-3, the probability of significant icing across the
    CONUS is less than 10 percent.


    Fracasso/Snell





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  • From COD Weather Processor @1:2320/107 to All on Wed Oct 14 18:06:32 2026
    FOUS11 KWBC 141805
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    205 PM EDT Wed Oct 14 2026

    Valid 00Z Thu Oct 15 2026 - 00Z Sun Oct 18 2026

    ...Central Rockies...
    Day 1...

    The mid-level low near the Four Corners this morning will move
    into western Colorado later this afternoon and early evening. This
    system will weaken as it reaches the central Plains by Thursday.
    Additional light to moderate higher elevation snow is expected to
    impact to portions UT/CO/WY over the next 24 hrs, ending from west
    to east over Utah tonight and lastly over the CO Rockies tomorrow
    evening. Snow levels immediately ahead of the system are high
    (8000-10,000ft), but will gradually lower as the upper low moves
    overhead to about 6500-9000ft from UT to CO. Any significant
    snowfall accumulations are expected to remain in the elevated
    terrain, though this does include high passes like I-70/Eisenhower
    Tunnel at just over 11,000ft and Vail Pass at 10,666ft. WPC
    probabilities for at least an additional 8 inches of snow are >50%
    above 10,000ft in Uintas of UT, CO Rockies, and south-central WY.
    Some lighter accumulations could fall as low as 6000 or 7000 feet
    as the upper low moves overhead in southeast WY early Thursday. The
    highest additional amounts will be across the Medicine Bow and
    Park Range of northern CO, as well as the Uinta Mts in UT, where up
    to a foot is possible. WSSI-P for Moderate impacts also highlights
    these locations, but with 10-30% values.


    For days 1-3, the probability of significant icing across the
    CONUS is less than 10 percent.


    Fracasso/Snell



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  • From COD Weather Processor @1:2320/107 to All on Thu Oct 15 06:02:24 2026
    FOUS11 KWBC 150602
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    202 AM EDT Thu Oct 15 2026

    Valid 12Z Thu Oct 15 2026 - 12Z Sun Oct 18 2026

    ...Central Rockies...
    Day 1...

    The upper-level low responsible for periods of snow above 6,000ft
    in northern CO and southern WY will exit east and weaken as it
    departs the region today. Some light snow will fall as low as
    ~6,000ft and could affect travel along I-25 in southeast WY. The
    heaviest snowfall (>4") is confined to elevations above 8,000ft.
    The latest 00Z HREF guidance shows moderate-to-high chances
    (50-80%) for 1"/hr snowfall rates around Rocky Mountain Nat'l Park
    and along the Laramie and Medicine Bow mountains this morning.
    Additional snowfall accumulations in the mountains above 8,000ft
    will range between 3-6" with elevations as low as 6,000ft seeing a
    coating-2". Rates will steadily taper off around midday and
    conditions will improve at all pass levels in northern CO and
    southern WY from late morning and into the afternoon.

    For days 1-3, the probability of significant icing across the
    CONUS is less than 10 percent.


    Mullinax




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  • From COD Weather Processor @1:2320/107 to All on Thu Oct 15 17:24:44 2026
    FOUS11 KWBC 151724
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    124 PM EDT Thu Oct 15 2026

    Valid 00Z Fri Oct 16 2026 - 00Z Mon Oct 19 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent


    Snell


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  • From COD Weather Processor @1:2320/107 to All on Fri Oct 16 06:21:36 2026
    FOUS11 KWBC 160621
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    221 AM EDT Fri Oct 16 2026

    Valid 12Z Fri Oct 16 2026 - 12Z Mon Oct 19 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent


    Mullinax





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  • From COD Weather Processor @1:2320/107 to All on Fri Oct 16 18:07:42 2026
    FOUS11 KWBC 161807
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    207 PM EDT Fri Oct 16 2026

    Valid 00Z Sat Oct 17 2026 - 00Z Tue Oct 20 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent


    Snell


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  • From COD Weather Processor @1:2320/107 to All on Sat Oct 17 06:14:26 2026
    FOUS11 KWBC 170614
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    214 AM EDT Sat Oct 17 2026

    Valid 12Z Sat Oct 17 2026 - 12Z Tue Oct 20 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent


    Mullinax





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  • From COD Weather Processor @1:2320/107 to All on Sat Oct 17 18:40:12 2026
    FOUS11 KWBC 171839
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    239 PM EDT Sat Oct 17 2026

    Valid 00Z Sun Oct 18 2026 - 00Z Wed Oct 21 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent through Tuesday.


    Jackson


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  • From COD Weather Processor @1:2320/107 to All on Sun Oct 18 11:38:04 2026
    FOUS11 KWBC 180846
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    446 AM EDT Sun Oct 18 2026

    Valid 12Z Sun Oct 18 2026 - 12Z Wed Oct 21 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent through Tuesday.


    Mullinax





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  • From COD Weather Processor @1:2320/107 to All on Sun Oct 18 17:42:04 2026
    FOUS11 KWBC 181741
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    141 PM EDT Sun Oct 18 2026

    Valid 00Z Mon Oct 19 2026 - 00Z Thu Oct 22 2026

    The probability of significant snow and ice across the CONUS is
    less than ten percent through Tuesday.


    Snell


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  • From COD Weather Processor @1:2320/107 to All on Mon Oct 19 06:22:50 2026
    FOUS11 KWBC 190622
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    222 AM EDT Mon Oct 19 2026

    Valid 12Z Mon Oct 19 2026 - 12Z Thu Oct 22 2026

    ...Southern Sierra Nevada...

    Day 3...

    A highly anomalous upper-low off the Southern CA coast
    (standardized anomalies as much as -4 sigma at 500mb and 700mb by 12Z
    Wed) will work in tandem with an upper-level ridge over the
    Nation's Heartland to tap into rich tropical East Pacific moisture
    and direct this moisture at the Southwest U.S.. 850-500mb mean flow
    out of the south will provide a favorable setup for upslope-
    enhanced precipitation rates long the southern Sierra Nevada. That
    said, the antecedent air-mass is not overly cold and the colder
    temperatures within the closed low are well offshore. This will
    keep snowfall confined to the higher elevations of the southern
    Sierra Nevada on Wednesday (above 9,000ft). The Probabilistic
    Precipitation Portal (PPP) shows low chances (10-30%) for snowfall
    totals >4" above 10,000ft. The Probabilistic Winter Storm Severity
    Index (WSSI-P) also show low chances (10-30%) as low as 9,000ft in
    elevations. This could result in some slick conditions in the
    rugged terrain of the southern Sierra Nevada mid-week.


    Mullinax





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  • From COD Weather Processor @1:2320/107 to All on Mon Oct 19 18:57:22 2026
    FOUS11 KWBC 191856
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    256 PM EDT Mon Oct 19 2026

    Valid 00Z Tue Oct 20 2026 - 00Z Fri Oct 23 2026

    ...Southern Sierra Nevada...

    Day 2-3...

    An anomalously deep mid and upper-level low off the Southern CA
    coast (with progged heights below all values in the CFSR
    climatology for this time of year valid at 12Z Wednesday) will
    direct rich tropical moisture from the east Pacific into the
    Southwest U.S. mid to late week. At the same time, increasing
    diffluence coupled with a strong 110kt 300mb jet on the downstream
    flank of the mid/upper low will overspread southern California,
    allowing large scale forcing for ascent to become maximized. The
    fetch of tropical moisture combined with the increasing large scale
    forcing will lead to the development of widespread low elevation
    rain and high elevation snow across the region beginning Wednesday
    night and continuing through the day on Thursday. 850-500mb mean
    flow out of the south will foster a favorable setup for moderate to occasionally heavy precipitation rates along upslope favored
    terrain of the southern Sierra Nevada. However, the air mass in
    place ahead of the low is not overly cold and the colder
    temperatures within the closed low largely stay well offshore
    through the forecast period. As a result, most of the accumulating
    snow will fall above 8,000-9,000ft through 00Z Friday, with the
    highest amounts above 10,000-11,000ft.

    Probabilities for snowfall accumulations greater than 4" have
    increased to roughly 20-50% above 9,000ft, and 50-90% above
    10,000-11,000ft. Additionally, the probability for greater than 8"
    above 10,000-11,000ft is up to roughly 50-80 percent. The
    Probabilistic Winter Storm Severity Index (WSSI-P) shows low
    chances (10-30%) for moderate impacts as low as 9,000ft, and low to
    medium chances (30-50%) above 10,000-11,000ft. This all suggests
    that there could be slick and snow-covered roads and passes in the
    highest terrain of the southern Sierra Nevada mid to late week.


    Miller








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  • From COD Weather Processor @1:2320/107 to All on Tue Oct 20 07:12:04 2026
    FOUS11 KWBC 200711
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    311 AM EDT Tue Oct 20 2026

    Valid 12Z Tue Oct 20 2026 - 12Z Fri Oct 23 2026

    ...Southern Sierra Nevada...

    Days 2 & 3...

    A closed low off the Southern CA coast will tap into moisture
    originating from the tropical East Pacific and direct it northward
    into the Sierra Nevada both Wednesday and Thursday. The Sierra
    Nevada also reside beneath a potent 120kt+ jet streak that will
    provide upper-level ascent aloft in addition to the
    topographically-induced ascent that supports upslope-enhanced
    precipitation rates. The lack of a sufficiently cold air-mass and
    the closed low opening up upon approach on Thursday will confine
    the heaviest snowfall to be above 10,000ft, although some 3-6"
    amounts could occur as low as 9,000ft. The Probabilistic
    Precipitation Portal (PPP) depicts moderate-to-high chances
    (40-70%) for snowfall totals >8" and low chances (10-30%) for
    snowfall >12" at elevations above 10,000ft through Thursday night.
    The WSSI-P does show high chances (>70%) for Minor Impacts (winter
    driving conditions, use caution while driving) and low-to-moderate
    chances for Moderate Impacts (hazardous conditions, closures and
    disruptions possible) above 9,000ft. The lower SLRs (topping out
    between 10-11:1) will make for generally a heavy, wet snowfall in
    the Sierra Nevada.


    Mullinax



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  • From COD Weather Processor @1:2320/107 to All on Tue Oct 20 19:49:08 2026
    FOUS11 KWBC 201948
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    348 PM EDT Tue Oct 20 2026

    Valid 00Z Wed Oct 21 2026 - 00Z Sat Oct 24 2026

    ...Southern Sierra Nevada...

    Days 1-2...

    An anomalously deep closed low spinning off the coast of southern
    CA will direct a plume of tropical moisture from the eastern
    Pacific northward into the Sierra Nevada through mid to late week.
    As the low approaches the coast, a potent 120kt+ upper-level jet
    streak will overspread the region, leading to an increase in broad
    large scale forcing for ascent. The moisture combined with
    increasing dynamic forcing will lead to widespread moderate to
    occasionally heavy high elevation mountain snow from Wednesday
    evening/night through Thursday evening. Aiding precipitation
    production will be the modestly strong low to mid level flow
    favorably oriented to the rugged terrain of the Sierra Nevada,
    which will also support upslope-enhanced precipitation rates. In
    fact, the 12Z HREF/REFS both highlight the potential for bursts of
    heavier snow with probabilities of 20-40 percent for >1"/hr
    snowfall rates, mainly later Wednesday night into Thursday morning.
    With that being said, the lack of a sufficiently cold air mass
    ahead of the low in addition to the low filling and opening up as
    it lifts northeastward into the Great Basin Thursday into Friday
    will keep the heaviest snowfall confined to above 9,000-10,000ft.

    The Probabilistic Precipitation Portal (PPP) depicts moderate to
    high chances (40-80%) for snowfall totals >8" and low to moderate
    chances (20-50%) for snowfall >12" at elevations above
    9,000-10,000ft through Thursday night. The WSSI-P shows high
    chances (>70 percent) for Minor Impacts and low to moderate chances
    (30-70 percent) for Moderate Impacts mainly above 10,000-11,000ft.
    The enhanced moisture and marginal thermals in play will keep SLRs
    mostly below 11:1, which will make for a heavy, wet snowfall in
    the Sierra Nevada.

    As the system moves into the northern Intermountain West/Rockies
    Thursday night into Friday, locally heavy snow will be possible
    across some of the higher elevations of southwest MT, western WY, south- central ID, as well as the eastern Uintas in northeast UT and the
    San Juans in southwest CO.

    The probability of significant ice across the CONUS is less than 10
    percent.


    Miller


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  • From COD Weather Processor @1:2320/107 to All on Wed Oct 21 06:20:26 2026
    FOUS11 KWBC 210619
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    219 AM EDT Wed Oct 21 2026

    Valid 12Z Wed Oct 21 2026 - 12Z Sat Oct 24 2026

    ...Southern Sierra Nevada...
    Days 1-2...

    The closed upper-low off the Southern CA coast will direct a plume
    of tropical moisture at the Southwest U.S. today and into Thursday.
    Some of this moisture source will be directed at the southern
    Sierra Nevada where a combination of topographically-induced
    upslope flow and synoptic scale support in the form of a 120kt+
    250mb jet streak will aid in enhanced precipitation rates and
    mountain snow. Latest 00Z HREF/REFS probabilistic guidance shows low-to-moderate chances (30-50%) for >1"/hr snowfall rates
    Wednesday night and into Thursday morning. These snowfall rates
    will be observed higher up in the southern Sierra Nevada with most
    areas above 9,000ft witnessing these potential snowfall rates. Snow
    is expected to taper off Thursday night. The Probabilistic
    Precipitation Portal (PPP) does show moderate-to-high chances
    (50-80%) for snowfall totals >6" above 9,000ft in elevation, with
    low chances (10-30%) for snowfall amounts exceeding 12" above
    11,000ft. The WSSI shows Minor Impacts are anticipated for
    elevations at/above 9,000ft, indicating winter driving conditions
    are expected and to exercise caution when driving in at those
    elevations.

    ...Central Rockies...
    Days 2-3...

    The same closed low responsible for the heavy snow in the Sierra
    Nevada will work in tandem with upper-level ridging over the
    South Central U.S. to project an impressive IVT into the
    Intermountain West. By 18Z Thursday, the IVT is surpassing 500
    kg/m/s in eastern AZ and eastern UT, which is surpassing the
    maximum observed values in the CFSR climatology (1979-2009). This
    highly anomalous moisture transport will upslope into various
    mountain ranges throughout the Intermountain West (San Juan, NV
    Great Basin ridge, Wasatch, Wind River, Tetons, Absaroka). Most
    accumulations will be on the minor side given the lack of a
    sufficiently cold air-mass. Thursday is the snowier day for the San
    Juan Mountains, while Friday is the snowier day for the mountains
    ranges across UT, NV, ID, southwest MT, and western WY.

    Latest PPP shows low-to-moderate chances (30-50%) for snowfall
    totals >6" in the more remote elevations of the San Juan, Teton,
    Wind River, and Absaroka Ranges. Localized snowfall amounts
    approaching 12" in the peaks on the San Juan Mountains are
    possible, especially where hourly snowfall rates >1"/hr occur. The
    WSSI-P shows <20% odds for Moderate Impacts throughout the
    Intermountain West. Some travel disruptions at pass levels are
    possible given the moderate-to-high chances (50-80%) for Minor
    Impacts in parts of the San Juan, Tetons, and Absaroka most
    notably.


    The probability of significant ice across the CONUS is less
    than 10 percent.


    Mullinax





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  • From COD Weather Processor @1:2320/107 to All on Wed Oct 21 18:21:30 2026
    FOUS11 KWBC 211821
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    221 PM EDT Wed Oct 21 2026

    Valid 00Z Thu Oct 22 2026 - 00Z Sun Oct 25 2026

    ...Southern Sierra Nevada...
    Days 1-2...

    The closed upper-low off the Southern CA coast will direct a plume
    of tropical moisture at the Southwest U.S. this evening and into
    Thursday. Some of this moisture source will be directed at the
    southern Sierra Nevada where a combination of topographically-
    induced upslope flow and synoptic scale support in the form of a
    120kt+ 250mb jet streak will aid in enhanced precipitation rates
    and mountain snow. Latest 12Z HREF/REFS probabilistic guidance
    shows low-to-moderate chances (30-50%) for >1"/hr snowfall rates
    overnight and into Thursday morning. These snowfall rates will be
    observed higher up in the southern Sierra Nevada with most areas
    above 9,000ft witnessing these potential snowfall rates. Snow is
    expected to taper off Thursday night as the upper low shifts to the north-northeast. The Probabilistic Precipitation Portal (PPP) does
    show moderate- to- high chances (40-80%) for snowfall totals >6"
    above 9,000ft in elevation, with low chances (10-30%) for snowfall
    amounts exceeding 12" above 11,000ft. The WSSI shows Minor Impacts
    are anticipated for elevations at/above 9,000ft, indicating winter
    driving conditions are expected and to exercise caution when
    driving in at those elevations.

    ...Northern & Central Rockies...
    Days 2-3...

    The same closed low responsible for the heavy snow in the Sierra
    Nevada will work in tandem with upper-level ridging over the
    South Central U.S. to project an impressive IVT into the
    Intermountain West. By 18Z Thursday, the IVT is surpassing 500
    kg/m/s in northeastern AZ and eastern UT, which is surpassing the
    maximum observed values in the CFSR climatology (1979-2009). This
    highly anomalous moisture transport will upslope into various
    mountain ranges throughout the Intermountain West (San Juan, NV
    Great Basin ridge, Wasatch, Wind River, Tetons, Absaroka). Most
    accumulations will be on the minor side given the lack of a
    sufficiently cold air-mass and high snow-levels. In fact, snow
    levels start above 13,000ft tonight across the San Juans and even
    over 11,000ft over the northern Rockies once precipitation enters
    the region Friday morning. Snow levels decline by Friday evening to
    around 5,000-6,000ft in the northern Rockies and 8,000ft-10,000 ft
    in the central Great Basin/Rockies. Still, thursday is the snowier
    day for the San Juan Mountains, while Friday is the snowier day
    for the mountains ranges across UT, NV, ID, southwest MT, and
    western WY as the moisture surge crosses the region.

    Latest PPP shows low-to-moderate chances (30-50%) for snowfall
    totals >6" in the more remote high elevations of the San Juan,
    Teton, Wind River, and Absaroka Ranges. Localized snowfall amounts
    approaching 12" in the peaks on the San Juan Mountains are
    possible, especially where hourly snowfall rates >1"/hr occur. The
    WSSI-P shows <20% odds for Moderate Impacts throughout the
    Intermountain West. Some travel disruptions at pass levels are
    possible given the moderate-to-high chances (50-80%) for Minor
    Impacts in parts of the San Juan, Tetons, and Absaroka most
    notably.


    The probability of significant ice across the CONUS is less
    than 10 percent.


    Mullinax/Snell


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  • From COD Weather Processor @1:2320/107 to All on Thu Oct 22 07:26:44 2026
    FOUS11 KWBC 220726
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    326 AM EDT Thu Oct 22 2026

    Valid 12Z Thu Oct 22 2026 - 12Z Sun Oct 25 2026

    ...High Sierra Nevada...
    Day 1...

    A low pressure system tracks east-northeast from the central
    California coast this morning to central Nevada by this evening. A
    strong moisture plume in advance will continue to produce heavy
    precip with snow levels around 9000ft on the southern Sierra Nevada
    rest of tonight. Light to moderate snow can be expected this
    afternoon under the upper low with snow levels dipping to around
    8000ft. Snow tapers off this evening. Day 1 probs for >4"
    additional snow after 12Z are 30-60% on the High Sierra.

    ...Northern Rockies...
    Day 2...

    The low crossing Nevada tonight opens into a neutrally-tilted
    trough as it tracks northeast over Idaho and Montana on Friday.
    Warm air advection ahead of the low brings moderate precip rates,
    but high snow levels over 9000ft at onset Friday morning with
    levels dropping to around 6000ft Friday afternoon under the trough
    axis in ID/MT (and staying 8000ft through the event in Wyoming).
    Day 2 snow probs for >4" are 30-70% for higher terrain from
    central ID through west-central MT as well as the Tetons and Wind
    River in WY. Most guidance highlights the Beartooth range in
    southwest MT where a foot of snow is possible.

    ...Colorado...
    Days 1-3...

    Warm air advection over the San Juans in CO brings moderate to
    heavy precip into Friday morning. Snow levels are exceedingly high,
    around 13,000ft today before dipping to 11,000ft tonight. Day 1
    snow probs for >4" are 30-60% for the highest terrain with Day 2
    around 20% for lingering snow Friday morning.

    A shortwave that breaks open the low over the Great Basin tonight
    swings over southern CA Friday before stalling/closing into a low
    over the lower CO River Friday night. This low then tracks to
    southern UT through Saturday night. Moderate precip rates return
    ahead of the low with snow levels dropping to around 9000ft with
    height falls. Day 3 snow probs for >4" are 40-80% for much of the
    San Juans and 30-70% for the Sawatch and Mosquito Ranges in central
    CO.


    The probability of significant ice across the CONUS is less
    than 10 percent.


    Jackson



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  • From COD Weather Processor @1:2320/107 to All on Thu Oct 22 18:22:24 2026
    FOUS11 KWBC 221822
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    222 PM EDT Thu Oct 22 2026

    Valid 00Z Fri Oct 23 2026 - 00Z Mon Oct 26 2026

    ...High Sierra Nevada...
    Day 1...

    A low pressure system tracking northeast from central Nevada this
    evening into the Pacific Northwest late tonight is producing
    periods of heavy snow across the High Sierra Nevada. The departure
    of the low will result in tapering snowfall rates, with little
    additional accumulation expected this evening.

    ...Northern Rockies...
    Days 1-2...

    The low crossing Nevada tonight opens into a neutrally-tilted
    trough as it tracks northeast over Idaho and Montana on Friday.
    Warm air advection ahead of the low brings moderate precip rates,
    but high snow levels over 9,000ft at onset Friday morning with
    levels dropping to around 5,500ft Friday afternoon under the
    trough axis in ID/MT (and staying above 8,000ft through the event
    in Wyoming) will greatly limit the areal coverage of
    significant accumulations to the higher summits . Day 1 snow probs
    for >4" are 40-80% for higher terrain from central ID through
    west-central MT as well as the Tetons and Wind River in WY. Most
    guidance highlights the Beartooth range in southwest MT where a
    foot of snow is possible.

    ...Colorado...
    Days 1-3...

    Warm air advection over the San Juans in CO brings moderate to
    heavy precip into Friday morning. Snow levels are exceedingly high,
    around 13,000ft today before dipping to 11,000ft tonight. Day 1
    snow probs for >4" are 40-80% for the highest terrain.

    A shortwave that breaks open the low over the Great Basin tonight
    swings over southern CA Friday before stalling/closing into a low
    over the lower CO River Friday night. This low then tracks to
    southern UT through Saturday night. Moderate precip rates return
    ahead of the low with snow levels dropping to around 9,500ft with
    height falls. Day 3 snow probs for >4" are 60-100% for much of the
    San Juans and 50-80% for the Sawatch and Mosquito Ranges in
    central CO.


    The probability of significant ice across the CONUS is less
    than 10 percent.


    Wegman






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  • From COD Weather Processor @1:2320/107 to All on Fri Oct 23 07:12:44 2026
    FOUS11 KWBC 230712
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    312 AM EDT Fri Oct 23 2026

    Valid 12Z Fri Oct 23 2026 - 12Z Mon Oct 26 2026


    ...Northern Rockies...
    Day 1...

    Neutrally-tilted trough tracks northeast from central Nevada over
    Idaho and Montana through this evening. Warm air advection ahead
    of the low brings moderate precip rates, but high snow levels over
    9,000ft this morning with levels dropping to around 6000ft this
    afternoon under the trough axis in ID/MT (while staying above
    7500ft through the event in Wyoming) will limit significant
    accumulations to the higher summits. Banding is expected as snow
    levels drop to around 5000ft in west-central MT this evening before
    tapering off. Day 1 snow probs for >6" are 40-70% for higher
    terrain from central ID through southwest MT with up to 80% for the
    Tetons and Wind River in WY and the Beartooth range in southwest
    MT where 10" snow is possible. Precip weakens and shifts east late
    tonight, bringing a quick end to accumulating snow.


    ...Colorado...
    Days 1-2...

    Main band of heavy precip has shifted east of the San Juans in CO
    early this morning. brings moderate to heavy precip into Friday
    morning. Snow levels are high, around 11,000ft today. Day 1 snow
    probs for >4" are 40-80% for the highest terrain.

    A southern shortwave trough closes into a low over the CA/AZ border
    this evening before tracking to the Four Corners through Sunday.
    Snow levels drop to around 9000ft with moderate precip rates. Day
    2 snow probs for >6" are 50-80% for much of the San Juans and
    30-50% for the Sawatch and Mosquito Ranges in central CO. The
    precip plume shifts east of the Rockies by Sunday night.



    The probability of significant ice across the CONUS is less
    than 10 percent.


    Jackson


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  • From COD Weather Processor @1:2320/107 to All on Fri Oct 23 19:40:22 2026
    FOUS11 KWBC 231939
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    339 PM EDT Fri Oct 23 2026

    Valid 00Z Sat Oct 24 2026 - 00Z Tue Oct 27 2026


    ...Northern Rockies...
    Day 1...

    An upper trough will move out of southwestern MT this evening and
    into Canada overnight. Ongoing mountain snow will accumulate
    several inches after 00Z above about 5000ft or so before ending
    06-09Z. Snow could fall moderate-heavy at times in banded areas
    with 1"/hr rates around 00Z this evening. WPC probabilities for at
    least an additional 4 inches of snow are highest (>50%) above
    5000ft.


    ...Colorado...
    Days 1-2...

    Southern portion of the northern upper trough will split off and
    dig through the lower CO River Valley Saturday before lifting
    across the Four Corners region Sunday. Southerly flow will bring in
    a moderate moisture plume but with high snow levels around
    11,000ft Saturday. Those will fall to around 9000ft with increasing
    snow rates and modest snow accumulations in the higher terrain of
    the San Juans and CO ranges. There, WPC probabilities for at least
    8 inches of snow are >50% above about 10,000ft or so. Snow will
    lighten and end from southwest to northeast on Sunday night.

    For Day 3, the probability of significant snowfall across the
    CONUS is less than 10 percent.

    For Days 1-3, the probability of significant ice across the CONUS
    is less than 10 percent.


    Fracasso

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  • From COD Weather Processor @1:2320/107 to All on Sat Oct 24 06:43:26 2026
    FOUS11 KWBC 240642
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    242 AM EDT Sat Oct 24 2026

    Valid 12Z Sat Oct 24 2026 - 12Z Tue Oct 27 2026

    ...Colorado...
    Day 1...

    Mid-level low over southern California lifts northeast to the Four
    Corners through tonight. Southerly flow in advance will bring
    moderate precip rates and high snow levels over Colorado around
    11,000ft today before dropping to 9000ft tonight as rates decrease
    under height falls. Day 1 PWPF for >6" snow are 30-60% in the
    higher Sangre de Cristo, Sawatch, and Mosquito ranged and 50-90%
    for the higher San Juans.


    ...Northern Plains...
    Day 3...

    THe Four Corners low opens to a trough Sunday morning and ejects north-northeast and becomes positively tilted over the northern
    Plains on Monday. Enough comma head expansion of precip occurs to
    have some snow bands on the outer northwest side of the precip
    shield. This could intersect with the Black Hills and could also
    have dynamic enough banding for some snow accum in northwest
    South Dakota and central North Dakota. As of now the potential is
    for 1-2", but given the negative tilt and available cold air from a
    Canadian Prairies surface high, some decent snow banding may
    occur.


    For Days 1-3, the probability of significant ice across the CONUS
    is less than 10 percent.


    Jackson



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  • From COD Weather Processor @1:2320/107 to All on Sat Oct 24 18:46:34 2026
    FOUS11 KWBC 241846
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    246 PM EDT Sat Oct 24 2026

    Valid 00Z Sun Oct 25 2026 - 00Z Wed Oct 28 2026

    ...Colorado...
    Day 1...

    An upper low over northwestern Arizona this evening will lift
    northeastward across the Four Corners overnight. Southerly flow in
    advance of the low will bring moderate precip rates and high snow
    levels over Colorado around 9000ft tonight as rates decrease under
    height falls. The probabilities for an additional 6 inches of snow
    after 00Z are highest in the higher Sangre de Cristos and
    especially the higher San Juan Mountains.


    ...Northern Plains...
    Days 2-3...

    The Four Corners low will mostly open to a trough by Monday and
    eject across the northern Plains. With surface low pressure moving
    across eastern SD Monday night, enough comma head expansion of
    precip should occur to have some snow bands on the outer northwest
    side of the precip shield. This could intersect with the Black
    Hills and could also have dynamic enough banding for some snow
    accumulation in northwestern South Dakota and south central North
    Dakota. Temperatures are marginal, but any snow that falls before
    sunrise would have a better chance of accumulating. Most likely
    forecast is for a broad T-0.5" snow with some potential for an axis
    of 1-2" from the Black Hills northeastward. The probability of at
    least 2" from the Probabilistic Precipitation Portal is about
    20-55% along the ND/SD border southwest of Bismarck, but the 90th
    percentile is around 4".


    For Days 1-3, the probability of significant ice across the CONUS
    is less than 10 percent.


    Fracasso/Jackson


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  • From COD Weather Processor @1:2320/107 to All on Sat Oct 24 19:21:36 2026
    FOUS11 KWBC 241921
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    321 PM EDT Sat Oct 24 2026

    Valid 00Z Sun Oct 25 2026 - 00Z Wed Oct 28 2026

    ...Colorado...
    Day 1...

    An upper low over northwestern Arizona this evening will lift
    northeastward across the Four Corners overnight. Southerly flow in
    advance of the low will bring moderate precip rates and high snow
    levels over Colorado around 9000ft tonight as rates decrease under
    height falls. The probabilities for an additional 6 inches of snow
    after 00Z are highest in the higher Sangre de Cristos and
    especially the higher San Juan Mountains.


    ...Northern Plains...
    Days 2-3...

    The Four Corners low will mostly open to a trough by Monday and
    eject across the northern Plains. With surface low pressure moving
    across eastern SD Monday night, enough comma head expansion of
    precip should occur to have some snow bands on the outer northwest
    side of the precip shield. This could intersect with the Black
    Hills and could also have dynamic enough banding for some snow
    accumulation in northwestern South Dakota and south central North
    Dakota. Temperatures are marginal, but any snow that falls before
    sunrise would have a better chance of accumulating. Most likely
    forecast is for a broad T-0.5" snow with some potential for an axis
    of 1-2" from the Black Hills northeastward. The probability of at
    least 2" from the Probabilistic Precipitation Portal is about
    20-55% along the ND/SD border southwest of Bismarck, but the 90th
    percentile is around 4".

    ...Northern Rockies...
    Day 3...

    An upper low along the WA/OR coast Monday will push inland and
    cross the Divide early Tuesday, spreading valley rain and mountain
    snow to Wyoming, Idaho, and western Montana. Snow levels will hover
    around 5000-7000ft through Tuesday evening with snow continuing
    into early Wednesday. The probability of at least 6 inches of snow
    by 00Z Wednesday is >50% above about 8000ft where liquid amounts
    will be highest as well.


    For Days 1-3, the probability of significant ice across the CONUS
    is less than 10 percent.


    Fracasso/Jackson





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  • From COD Weather Processor @1:2320/107 to All on Sun Oct 25 08:07:58 2026
    FOUS11 KWBC 250807
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    407 AM EDT Sun Oct 25 2026

    Valid 12Z Sun Oct 25 2026 - 12Z Wed Oct 28 2026

    ...Colorado...
    Day 1...

    An upper low over northern Arizona will open into a trough as it
    lifts northeast to Colorado through today. Height falls will bring
    snow levels down to around 9000ft today over CO terrain. Showery
    activity will lead to additional accumulation. Snow probs for >4
    inches additional after 12Z are 30-60% in the higher Sangre de
    Cristo and San Juan Mountains.


    ...Northern Plains...
    Days 2-3...

    The upper low crossing Colorado today will open to a trough that
    takes on a negative-tilt Monday as it lifts over the Northern
    Plains. The surface low track is across Kansas and eastern
    Nebraska Monday with enough comma head precip expansion to have
    some snow bands on the northwest side of the precip shield. This
    should intersect with the Black Hills Monday along with dynamic
    enough banding for some snow accumulation in northwestern South
    Dakota and south-central North Dakota. Temperatures are marginal,
    but any snow that falls before sunrise would have a better chance
    of accumulating. Most likely forecast is for a broad swath of T-0.5"
    snow with some potential for an axis of 1-2" from the Black Hills northeastward. Day 2 WPC snow probability of at least 2" is 20-30%
    in the Black Hills.


    ...Cascades and Northern Rockies...
    Days 1-3...

    An upper low reaches the WA/OR coast this afternoon with a series
    of reinforcing shortwave troughs maintaining low pressure over the
    Northwest states for much of the next week. Snow levels are
    generally 6000ft in the Cascades. A thermal gradient is apparent
    over west-central MT with snow levels down to 3000ft east of MT
    terrain and around 8000ft in ID and WY. Day 1 snow probs for >6"
    are 40-60% in the highest southern WA and OR Cascades. Day 2.5 snow
    probs for >6" 30-50% for the Tetons up along the ID/MT border
    terrain. Day 3 snow probs for >6" are farther north over the WA
    Cascades and north west MT ranges in/near Glacier NP.



    For Days 1-3, the probability of significant ice across the CONUS
    is less than 10 percent.


    Jackson


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  • From COD Weather Processor @1:2320/107 to All on Sun Oct 25 18:57:52 2026
    FOUS11 KWBC 251857
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    257 PM EDT Sun Oct 25 2026

    Valid 00Z Mon Oct 26 2026 - 00Z Thu Oct 29 2026

    ...Colorado...
    Day 1...

    Exiting upper low moving through Colorado tonight will bring an
    additional few inches to elevations above 9000ft before ending by
    12Z Monday.


    ...Northern Plains...
    Days 1-2...

    As the upper low over Colorado weakens to a trough overnight, a
    surface low will track across Kansas and eastern Nebraska Monday
    with enough comma head precip expansion to have some snow bands on
    the northwest side of the precip shield. This should intersect with
    the Black Hills Monday along with dynamic enough banding for some
    snow accumulation in northwestern South Dakota and south-central
    North Dakota. Temperatures are marginal, and the trend was been a
    bit slower such that most snow would fall between 18-00Z when it is
    less likely to stick. However, any snow that falls before sunrise
    or after sunset Monday would have a better chance of accumulating.
    Most likely forecast is for a broad swath of T-0.5" snow with some
    potential for an axis of 1-2" from the Black Hills northeastward.
    WPC probabilities of at least 4 inches of snow are about 10% in
    over parts of central SD and around 20-40% for at least 2" of snow.


    ...Cascades and Northern Rockies...
    Days 1-3...

    A modestly robust upper low just west of the WA coast this evening
    will move inland into the northern Great Basin on Monday with trailing/reinforcing shortwave troughs maintaining low pressure
    over the Northwest states for much of the week. Higher snow levels
    above 5000-8000ft ahead of the initial upper low Monday will lower
    to 4000-5500ft or so by Wednesday as another stronger upper low
    dips in from the BC coast, which could push snow levels to around
    3500ft over the WA Cascades. WPC probabilities for at least 8
    inches of snow over the next three days are >50% above about
    5000-6000ft from north to south along the Cascades from WA to OR,
    and about 5000ft over Idaho and western MT. Over northwestern WY,
    snow levels will be higher and significant snow will be above
    9000ft.

    By Wednesday, snow will likely start to fall at some of the pass
    levels including Washington, Stevens, and also Snoqualmie Passes.
    The probability of at least 2 inches of snow at Snoqualmie Pass
    through 00Z Thu is about 70%.


    For Days 1-3, the probability of significant ice across the CONUS
    is less than 10 percent.


    Fracasso


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