Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
417 PM EDT Sun May 05 2019

Valid 00Z Mon May 06 2019 - 00Z Thu May 09 2019


...Northern and Central Rockies...

Overall, expect the Day 1 period (ending 00Z Tue) to be fairly
quiet with respect to snow - with scattered snow showers producing
mainly light accumulations across portions of the southwestern
Montana and northwestern Wyoming ranges. 

However, with a well-defined shortwave approaching from the
northwest, snow showers and the potential for significant
accumulations will start to become more widespread on Day 2
(ending 00Z Wed), with WPC guidance indicating a pair of Slight
Risk areas for accumulations of 8-inches or more for portions of
the Absaroka and Wind River Ranges.  Meanwhile, a weakening upper
low moving across the lower Colorado Basin will begin to introduce
mainly light accumulations along the Wasatch into the Uinta
Mountains. 

Mountain snows will continue into Day 3 (ending 00Z Thu) from
western into central Wyoming.  Amplifying northeasterly flow on
the backside of a low level wave dropping southeast across Wyoming
into northeast Colorado will help support some locally heavy
amounts, with WPC guidance showing a Moderate Risk for 8-inches or
more and Slight Risk for accumulations of 12-inches or more along
the Wind River Range.  To the south, snows will continue along
portions of the Wasatch and Uinta Mountains while spreading
farther east into Colorado, with significant accumulations
possible for portions of the Sawatch and San Juan Mountains. 
Developing upslope flow west of a low spinning up over the High
Plains will begin to produce snow east of the Divide along the
Front Range on Wednesday.  

The probability of significant icing is less than 10 percent.

Pereira