FOUS11 KWBC 190622
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
222 AM EDT Mon Oct 19 2026

Valid 12Z Mon Oct 19 2026 - 12Z Thu Oct 22 2026

...Southern Sierra Nevada...

Day 3...

A highly anomalous upper-low off the Southern CA coast
(standardized anomalies as much as -4 sigma at 500mb and 700mb by 12Z
Wed) will work in tandem with an upper-level ridge over the 
Nation's Heartland to tap into rich tropical East Pacific moisture 
and direct this moisture at the Southwest U.S.. 850-500mb mean flow
out of the south will provide a favorable setup for upslope- 
enhanced precipitation rates long the southern Sierra Nevada. That 
said, the antecedent air-mass is not overly cold and the colder 
temperatures within the closed low are well offshore. This will 
keep snowfall confined to the higher elevations of the southern 
Sierra Nevada on Wednesday (above 9,000ft). The Probabilistic 
Precipitation Portal (PPP) shows low chances (10-30%) for snowfall 
totals >4" above 10,000ft. The Probabilistic Winter Storm Severity 
Index (WSSI-P) also show low chances (10-30%) as low as 9,000ft in 
elevations. This could result in some slick conditions in the 
rugged terrain of the southern Sierra Nevada mid-week.


Mullinax





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