• Rockies Winter Storm

    From Mike Powell@CAPCITY2 to All on Thu Oct 17 08:58:00 2024
    FOUS11 KWBC 170836
    QPFHSD

    Probabilistic Heavy Snow and Icing Discussion
    NWS Weather Prediction Center College Park MD
    436 AM EDT Thu Oct 17 2024

    Valid 12Z Thu Oct 17 2024 - 12Z Sun Oct 20 2024

    ...Mountain West... Days 1-3...

    **First Significant Winter Storm of the Season to Impact much of
    the Rockies**

    A shortwave trough crossing the PacNW coast this morning will dig
    across the Great Basin tonight before closing into a low over
    northern Arizona by Friday. This low then stalls/drifts east
    through Saturday. Ascent ahead of this trough today will allow
    widespread rain and high elevation snow today over the Great Basin
    and the northern Absarokas where snow levels will be around
    7000ft.

    Snow levels ahead of the upper low will be quite high, generally
    9000-10000ft over CO and southern WY through Saturday. However,
    rapid cooling beneath the approach of the upper low and behind the
    cold front should drive snow levels to as low as 4000 ft across the
    Great Basin, and 5000-6000ft in UT/northern WY. High moisture flux
    ahead of the low means heavy snow is likely to begin just above
    these levels.

    Day 1 snow probs are over 50% for >8" over the northern Absarokas
    and Uinta, spreading through the Wind Rivers/Wasatch Friday/Day
    1.5. Day 2 features over 80% probs for >8" in the higher San Juans
    of CO where Day 3 probs are around 50% in the prolonged precip
    ahead of the stalled low. Major accumulations are likely much of
    across the San Juans with local maxima of 2-4 feet. These areas
    are also where the greatest impacts are expected as the combination
    of modest SLR but heavy precipitation causes WSSI to feature
    major impacts during this early season storm.


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

    Jackson


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