• Winter Storm Continues SW

    From Dumas Walker@21:1/175 to All on Friday, March 15, 2024 09:10:00
    FOUS11 KWBC 150714

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    314 AM EDT Fri Mar 15 2024

    Valid 12Z Fri Mar 15 2024 - 12Z Mon Mar 18 2024

    ...Southern Rockies, Four Corners, and the Southwest...
    Days 1-3...

    ***Heavy snow wanes along the Front Range but continues across the
    Four Corners through the weekend***

    The impressive snow event across the Front Range due to long-
    duration and robust upslope flow will begin to wind down today as
    the best ascent shifts southward, and mid-level flow begins to
    return to the south. This should bring a slow end to the upslope
    component of this event, although this will be at the expense of a
    larger scale event which begins in earnest across the Four
    Corners. Additional snow in the Front Range and Sangre de Cristos
    D1 only has a 30-60% chance of exceeding an additional 4 inches.

    Meanwhile, as precipitation across the Front Range begins to wane,
    the parent upper low sinking south towards the Desert Southwest
    will begin to exert its influence across the region. The deep low
    with height anomalies nearing -3 sigma according to NAEFS will
    spread pronounced and long-lasting mid-level divergence downstream
    from the lower CO Basin through the Central High Plains. Confluent
    flow southeast of this low will help surge moisture northward,
    combining with modest jet-level diffluence to expand moderate to
    heavy precipitation through Saturday. This will result in heavy
    snowfall in much of the terrain from the Mogollon Rim and Kaibab
    Plateau eastward into the Wasatch, San Juans, and Sangre de
    Cristos, with heavy snow accumulations likely above snow levels of
    6000-8000 ft in the region of strongest WAA/heaviest precip, but
    may fall to 4000-5000 ft beneath the cold core low, especially as
    it begins to eject east by Sunday. WPC probabilities for more than
    6 inches D1 are above 90% in the southern Wasatch and much of the
    San Juans, as well as the higher terrain of the Mogollon Rim, and
    White Mountains, with additional low to moderate probabilities
    (20-60%) fore 6+ additional inches on D2 across much of the same

    As the upper low finally begins to fill and eject eastward through
    the Four Corners on Sunday, total forcing for ascent and moisture
    should begin to wane. However, still sufficient moisture and
    persistent ascent both due to height falls and steepening lapse
    rates aloft will allow for precip falling as snow to continue to
    pivot eastward, primarily falling in the San Juans and Sangre de
    Cristos D3. Additional snowfall D3 is confined to the San Juans and
    Sangre de Cristos, where WPC probabilities for 6+ inches are again
    20-40%. 3-day snowfall in some of the higher terrain of the Wasatch
    and San Juans will likely reach 2-3 feet.

    ...Great Lakes and New England...
    Day 3...

    A surface low pressure moving through Ontario and Quebec will drive
    a cold front through the Great Lakes, Ohio Valley, and into New
    England. Some modest moist advection will occur downstream and
    ahead of this front resulting in a narrow corridor of heavy
    precipitation lifting northeast into New England on Sunday. Much of
    this will likely fall as rain in the marginally favorable thermal
    structure of the column, but across northern NH and into northern
    ME, especially in higher elevations, WPC probabilities for more
    than 4 inches of snow are 10-30%.

    More impressive, although still somewhat modest, is likely to be an
    increase in lake effect snow (LES) behind the front as strong CAA
    surges southeast across the Great Lakes. This will result in axes
    of significant snowfall accumulations in the favored N/NW snow
    belts across the U.P. of MI, and along the Chautauqua Ridge and
    Tug Hill Plateau. WPC probabilities within the LES bands are as
    high as 20-30% downwind of Lakes Superior, Erie, and Ontario,
    highest across the U.P. of MI.

    The probability of receiving at least 0.1" ice is less than 10%
    across the CONUS through Day 3.


    **Key Messages for the March 13-16 Winter Storm can be found on our
    website at https://www.wpc.ncep.noaa.gov **

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