• Heavy, Disruptive Snow CA

    From Mike Powell@618:250/1 to All on Wed Feb 18 08:37:30 2026
    FOUS11 KWBC 180838
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    338 AM EST Wed Feb 18 2026

    Valid 12Z Wed Feb 18 2026 - 12Z Sat Feb 21 2026

    ...Pacific & Interior Northwest... Days 1-2...

    The longwave trough that has led to multiple days worth of
    accumulating snowfall looks to continue through at least Thursday
    morning before a upper level ridge pattern builds in late in the
    day Thursday and persist through Friday. Snow levels along I-5 will
    creep as far down as 500ft this morning and again on Thursday
    morning, but moderate-to-locally heavy snow will reside in the
    2,000ft elevations of the OR Cascades and above 3,000ft in the WA
    Cascades. Farther east, the Blue Mountains on east into the
    Bitterroots and Sawtooths will be heavy snow above 3,000ft (Blues & Bitterroots) and above 4,000ft (Sawtooth). The heaviest snowfall
    will unfold in the Absaroka, Tetons, Wind River, and Bear River
    Ranges where they not only have the higher elevations, but also
    reside where the riches 700-300mb moisture source will be and
    beneath the diffluent left-exit region of a 250-500mb layer jet
    streak. WPC probabilities moderate-to-high chances (40-70%) for
    snowfall >12" in the peaks of these mountains ranges, as well as
    the peaks of the OR Cascades. In the Willamette Valley, most
    snowfall totals are likely to be less than 1", although some areas
    close to Eugene, OR could eclipse 1". Expect hazardous travel
    conditions in the passes of the Northern Rockies and OR Cascades
    through Thursday morning.

    ...California... Days 1-2...

    ...Heavy, disruptive snowfall for the California ranges to persist
    through Thursday...

    California remains ideally placed ahead of 500mb disturbances
    rotating around the western flank of a large longwave trough
    anchored over the western U.S.. Snow levels in northern CA are as
    low as 1,000ft, down to 2,500 ft in the Sierra Nevada, and
    4,000-5,000 ft in the Transverse Ranges this morning. After a day
    generally upslope-driven snowfall on Wednesday, by Thursday, a
    phasing of shortwaves diving southeast from the Pacific NW coast
    will produce heavier snowfall totals throughout the CA mountain
    ranges. Similar to the Northwest, upper ridging will provide a
    break in the heavy snowfall threat beginning late Thursday and
    continuing into Friday.

    Additional snowfall of 1-2 feet are likely for the northern Sierra
    Nevada above 3,000ft, while in the southern Sierra, elevations
    above 4,000 can expect several more feet in the highest elevations.
    The WSSI continues to indicate widespread Major impacts are likely
    for just about all of the Sierra NEvada above 4,000ft Sierra
    Nevada through Thursday. This includes not only Donner Pass, but in
    the Shasta/Siskiyou where Moderate to locally Major Impacts are
    possible along I-5 mountain passes. In Southern California,
    additional snowfall accumulations over a foot are forecast above
    6,000ft in the Transverse Ranges with localized amounts exceeding 2
    feet possible in the peaks of the San Gabriel and San Bernadino
    Mountains through Thursday.

    ...Intermountain West/Southwest to the Rockies... Days 1-3...

    Pacific moisture spilling over the Cascades and Sierra-Nevada will
    provide a much-needed boost to the Intermountain and Rocky Mountain snowpack. Following a warm start, snow levels will drop into the valleys as
    the leading shortwave moves inland on Wednesday. A brief lull is
    expected on Thursday, except for Nevada and the Four Corners
    region, where the next shortwave will bring the threat for heavy
    mountain snow into Friday. Probabilities for storm total amounts
    over a foot exceed 70 percent for several areas including the high
    elevations of the Nevada mountains, the southern Utah mountains,
    the northern Arizona plateaus to the central Mogollon Rim, and much
    of the central Rockies - particularly the northern Utah and
    western Colorado ranges.

    ...Northern Plains & Upper Great Lakes... Days 1-2...

    The winter storm is ongoing this morning with heavy snow blanketing
    much of northern ND, northern MN, and into the northern tier of
    MI's Upper Peninsula. Heavy snow will continue to the north of the
    500mb low as it tracks across southern MN and into northwest WI,
    placing the MN Arrowhead perfectly placed beneath not just the
    strongest upper-level divergence, but easterly flow off Lake
    Superior is upsloping into the Arrowhead. Snowfall rates of 1-2"/hr
    will be common this morning and through midday but rates should
    gradually weaken this afternoon and tonight. The closed low will
    meander over the western MI U.P. through Thursday morning, keeping
    periods of light-to-moderate snow in the forecast over northern MN
    through Thursday morning. Snowfall totals of 1-2 feet are expected
    in the MN Arrowhead with localized amounts surpassing 30" possible
    by the time this storm concludes.

    Additionally, with the pronounced WAA rotating around the surface
    low, an area of freezing rain is also expected, especially from
    just south of Duluth, MN eastward across northern WI and into
    northern MI where the warm nose will be most prevalent while
    surface temps remain sub-freezing. This sets the stage for a
    freezing rain/icing event that could last over 24 hours in parts
    of northern WI and northern MI. WPC probabilities are moderate-to-
    high (50-80%) for at least 1/10 inch of ice, with locally more
    than a quarter inch possible, most likely across the tip of
    Michigan's Mitten, mainly areas east of Grand Traverse Bay.

    ...Northeast... Days 1-3...

    A strong surface low moving slowly across the Dakotas/Minnesota
    today will remain entrenched within an elongated mid-level trough
    extending into the Mid-Atlantic states. Vorticity lobes downstream
    of this wave will spread northeast from the Mid-Atlantic states
    into the Northeast, before getting sheared to the east as mid-level
    flow becomes strongly confluent south of the secondary shortwave
    energy crossing Maine and Nova Scotia. The resultant mid- level PVA
    and divergence will overlap with a narrow ribbon of impressive
    low-level WAA to produce a stripe of moderate-to- locally heavy
    precipitation from Upstate NY through southern/central New England.

    Periods of snow will unfold from the eastern shores of Lake Ontario
    going east across the Tug Hill, southern tier of the Adirondacks,
    and as far east as the Green and Berkshires. Snowfall totals are
    most likely to range between a coating to 3", although some
    localized totals topping 4" are possible in parts of the
    Adirondacks and Berkshires. While the atmosphere is likely to
    remain below freezing in these areas, a narrow warm- nose aloft
    from I-90 in western NY on east through the Catskills, Poconos, and
    even portions of southern New England are likely to see freezing
    rain. The section of western NY located along and north of I90,
    including the Rochester area, are most concerning when it comes to
    travel impacts. WPC probabilities show high chances (>70%) for ice accumulations over one-tenth of an inch there and low-to- moderate
    chances (20-50%) for totals over one- quarter inch. This area does
    show the potential for Moderate Impacts (hazardous driving
    conditions, closures possible) today. Farther east, most ice
    amounts are likely to come in under a tenth of an inch from the
    Finger Lakes on east through southern NY (not NYC proper), the
    Poconos, and southern New England, but localized Minor Impacts are
    denoted on the WSSI today.

    Following a brief break in the action Thursday, a storm system
    strengthening in the Midwest will direct a plume of 850-300mb
    moisture towards the Northeast amidst increasing WAA Thursday
    night. To the north, high pressure over southeast Canada is
    building in with a weak CAD signature forming over the region. This
    sets the stage for yet more ice from northern into the heart of
    the Northeast. The Poconos, Catskills, southern Adirondacks, and
    Berkshires have moderate chances (40-70%) for ice accumulations
    over one-tenth of an inch, while many areas from the Lehigh Valley
    on north and east into southern New England. The higher elevations
    of the Poconos and Catskills could see localized ice accumulations
    approach one-quarter inch. In the northern Appalachians, the
    atmosphere will remain cold enough to support periods of snow that
    look to fall heavily at times Friday and into Friday evening. WPC
    probabilities show moderate-to- high chances (50-70%) for snowfall
    totals >4" in the northern Adirondacks, Green, and White mountains
    with low chances (10-40%) for localized amounts surpassing 8".

    ...Central Plains... Days 1-2...

    Tonight, a potent shortwave trough ejecting out of the Central
    Rockies will take on a negative tilt as it heads into the Central
    Plains. To the north of the 500mb vort max, strong 700mb Q-vector
    confluence will focus a narrow area of strong vertical velocities,
    coinciding with a pronounced TROWAL forming over the Black Hills on
    east into the Sand Hills of NE early Thursday morning. Most
    guidance agrees the impressive synoptic-scale support aloft (left-
    exit region of a 250mb jet streak over head) and strong SErly 850mb
    WAA will support heavy snowfall rates, and confidence is
    increasing in the Black Hills and the Sand Hills being the hardest
    hit. Latest WPC probabilities show moderate chances (40-60%) for
    6" of snow in the Black Hills and Sand Hills on east along the
    NE/SD border and into southeast SD. It is worth noting there are low-to-moderate chance probabilities (20-50%) for >8" of snowfall
    in these areas as well. Given the strong dynamics and banding
    potential, localized totals surpassing 10" cannot be ruled out.
    Note that there does remain some uncertainty on the exact placement
    of the heavy snow banding, but guidance is in fairly good
    agreement a band of snow generating warning-level snowfall has
    moderate chances (40-60%) over western NE. Residents in the
    Central Plains should monitor the forecast from their local WFO
    closely in the coming days. Minor snowfall accumulating of 1-4" are
    possible as far west as east-central WY with some potential for
    4-6" worth of snow in eastern NE to the north of the Omaha area.

    Mullinax/Kleebauer/Pereira
    $$
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    * Origin: Capitol City Online (618:250/1)