FOUS11 KWBC 040859

QPFHSD



Probabilistic Heavy Snow and Icing Discussion

NWS Weather Prediction Center College Park MD

459 AM EDT Mon May 4 2026



Valid 12Z Mon May 04 2026 - 12Z Thu May 07 2026



...Sierra Nevada...

Day 1...



Upper low just over SF Bay will drift southeast to southern CA

through Tuesday before opening and ejecting east over AZ Tuesday

night. A modest plume of moisture will intersect the Sierra and 

promote light to locally modest snow for the higher elevations as 

snow levels remain around 8500ft. Snow will end Tuesday evening as

heights begin to rise. Day 1 WPC snow probabilities for >6" are 

>50% above about 8500ft. 





...Wyoming and Colorado...

Days 1-3...



Upper ridging continues to build north of the CA upper low and 

extends into the Yukon today, promoting downstream troughing to 

surge down the northern Plains through this afternoon. WSWly jet 

out of the Pacific subtropics will arc across the Four Corners 

region today and provide lift over the cold front that enters CO 

tonight. Snow levels of 9000 to 10,000ft will crash behind the cold

front on Tuesday as it shifts southward. Snow levels will lower 

over eastern CO to 6000-7000ft as the boundary dams up against east

of the Divide, keeping snow levels >8000ft on the west side. 

Modest to locally heavier snow should set up over parts of 

southern WY through CO via easterly/upslope flow (e.g., Laramie and

Medicine Bow Mountains) as the upper low pushing into central CA 

promotes lee-side troughing on the Rockies and some delay to the 

cold frontal passage. Precip shifts down the Rockies through Wednesday

night before shifting east onto the Plains. 



Day 1 WPC probabilities for >6" of snow are 40-80% over the 

highest Snowy Range in WY and Front Range in CO. Day 2 is the 

busiest day with renewed snow in both WY and CO including onto the 

High Plains/Denver and snow probs >8" 50-90% over the Front Range 

and generally 40-80% for the Wind River, Park Range, Pikes Peak, 

and higher portions of the Palmer Divide. Meanwhile snow probs for 

>4" are 20-40% over the CO High Plains. Day 3 snow probs highlight

the southward shift in the frontal pattern with 30-50% for >8" snow

in the Sangre de Cristos.





The probability for significant icing over one-tenth of an inch is

less than 10 percent across the CONUS. 





Jackson





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