Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
358 PM EDT Thu Oct 24 2019

Valid 00Z Fri Oct 25 2019 - 00Z Mon Oct 28 2019


Day 1...

...Texas/Oklahoma...
Intense frontogenetical band of snowfall will wane in the first
few hours of tonight as fgen weakens and ascent pulls off to the
northeast. Additional light snow accumulations are possible, with
WPC probabilities indicating a 10% chance for locally 2".


Days 2-3...

...Northern Rockies into Northern High Plains...
Longwave trough will deepen across the Mountain West Saturday as
multiple shortwaves embedded within the flow amplify the pattern.
Within this trough, a surface low will move across Southern Canada
driving a cold front rapidly southward from Montana through the
Central Plains, with secondary surface low development likely
dropping southeast through the Rockies. Forced ascent through
low-level upslope flow and height falls will produce snow in the
high terrain of Montana and Wyoming on Day 2, with snow pushing
into CO and the Nebraska Panhandle on Day 3 /Saturday night/. Snow
levels are progged to fall to below 2000 ft behind the cold front,
so much of the precipitation is expected to fall as snow in MT,
WY, northern CO, the Black Hills of SD, and the Panhandle of NE.
This is echoed by similarly high snow probabilities of the
ensembles. The highest chances for more than 8 inches of snow is
expected in the Big Horn and Laramie ranges of Wyoming due to
their elevation and being beneath the RRQ of an intensifying upper
jet streak late D2 into D3. It is this same jet streak that may
push a stripe of lighter snow as far east as Central Nebraska,
where WPC probabilities for 4 inches fall from near 80% in the
Panhandle to 10% near Valentine.

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

Weiss