Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
347 PM EDT Tue May 03 2022

Valid 00Z Wed May 04 2022 - 00Z Sat May 07 2022

...Northern to the Central Rockies...
Day 1...

Closed mid/upper level low currently over the Intermountain West
will reach the Colorado Rockies tomorrow before opening up into
the Plains late Wednesday night into Thursday. This will bring a
modest amount of lift across the region working with sufficient
moisture to produce some heavy for portions of the higher terrain
areas of the Northern to Central Rockies. A prolonged period of
upslope flow is expected against the central Idaho ranges
including the Wind River Range where the latest guidance showed a
substantial uptick in the QPF. The hi-res guidance appears a bit
overdone but going with a consensus still yields upwards of 1-2"
of QPF for some of the peaks in WY. As a result, even with lower
SLRs in place, there is a moderate signal for 8" across some of
the higher peaks of WY, northern CO, and northern UT Unitas with
the greatest focus/lift on the Wind River Range where isolated
totals 12-24" are possible.

...Pacific Northwest...
Day 3...

Nose of 130+ kt jet reaches southern OR/northern CA late Thursday
into Friday and the left exit region will bring lift across much
of the Pacific Northwest. With an ample moisture plume pushing
inland, several inches of snow are likely for the WA Cascades,
though confined to the higher peaks given relatively high snow
levels. The latest WPC snow probabilities show moderate signals
for 4 inches or more primarily for the highest peaks of the WA
Cascades.


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

Taylor