FOUS11 KWBC 220726
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 AM EDT Thu Oct 22 2026

Valid 12Z Thu Oct 22 2026 - 12Z Sun Oct 25 2026

...High Sierra Nevada... 
Day 1...

A low pressure system tracks east-northeast from the central 
California coast this morning to central Nevada by this evening. A
strong moisture plume in advance will continue to produce heavy
precip with snow levels around 9000ft on the southern Sierra Nevada
rest of tonight. Light to moderate snow can be expected this
afternoon under the upper low with snow levels dipping to around
8000ft. Snow tapers off this evening. Day 1 probs for >4"
additional snow after 12Z are 30-60% on the High Sierra. 

...Northern Rockies... 
Day 2...

The low crossing Nevada tonight opens into a neutrally-tilted
trough as it tracks northeast over Idaho and Montana on Friday.
Warm air advection ahead of the low brings moderate precip rates,
but high snow levels over 9000ft at onset Friday morning with
levels dropping to around 6000ft Friday afternoon under the trough
axis in ID/MT (and staying 8000ft through the event in Wyoming).  
Day 2 snow probs for >4" are 30-70% for higher terrain from 
central ID through west-central MT as well as the Tetons and Wind 
River in WY. Most guidance highlights the Beartooth range in 
southwest MT where a foot of snow is possible.

...Colorado...
Days 1-3...

Warm air advection over the San Juans in CO brings moderate to
heavy precip into Friday morning. Snow levels are exceedingly high,
around 13,000ft today before dipping to 11,000ft tonight. Day 1
snow probs for >4" are 30-60% for the highest terrain with Day 2
around 20% for lingering snow Friday morning. 

A shortwave that breaks open the low over the Great Basin tonight
swings over southern CA Friday before stalling/closing into a low
over the lower CO River Friday night. This low then tracks to
southern UT through Saturday night. Moderate precip rates return
ahead of the low with snow levels dropping to around 9000ft with
height falls. Day 3 snow probs for >4" are 40-80% for much of the
San Juans and 30-70% for the Sawatch and Mosquito Ranges in central CO.


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


Jackson



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