Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
247 PM EDT Sat Apr 22 2023

Valid 00Z Sun Apr 23 2023 - 00Z Wed Apr 26 2023

...Central Rockies...
Day 1...

A weakening vort max moving out CO this evening is expected to
produce a few additional hours of moderate snowfall across
southern CO tonight. More specifically, the Sangre de Cristo
Mountains are the epicenter for the heavy snowfall potential.
Here, WPC probabilities for at least 4 inches of snow are moderate
(>30%) until forcing rapidly weakens after about 06z Sunday.

...Pacific Northwest and northern/central Rockies...
Days 2-3...

A compact/small upper low is forecast to swing into coastal WA
late Sunday and continue southeastward into southern ID on Monday,
followed by northern UT early Tuesday while on a path to western
CO. Precipitable water values are forecast to only rise slightly
above climo values, but the combination of modest height falls and
upper divergence on the LFQ of the upper jet along with some
frontogenetical forcing in the lower levels will promote light to
moderate snow over the Cascades D2 and then across central
ID/southwestern MT/northern UT/CO Rockies D3 as the system
continues southeastward. Snow levels are expected to drop to
around 5000 ft across the northern Rockies on D2, with levels
remaining above 6000 ft across the central Rockies by the end of
D3. Some areas of southwestern MT may see more than six inches of
snow in elevations above 7000ft, where WPC probabilities are
moderate (>40%) for at least six inches.


The probability of significant icing greater than 0.25" is less
than 10 percent for Days 1-3.


Snell