Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
217 PM EDT Wed Apr 10 2024

Valid 00Z Thu Apr 11 2024 - 00Z Sun Apr 14 2024

...California...
Day 3...

A closed mid-level low diving along the Pacific coast will deepen
Saturday as it approaches central CA, evidenced by NAEFS 500-700mb
height anomalies falling to below -3 sigma. This will produce
impressive downstream divergence into CA D3, with ascent
additionally enhanced by strong LFQ diffluence as a jet streak
rotating around the base of this low surges to around 90kts. This
deep layer ascent will increasingly act upon a saturated column as
SW flow out of the Pacific surges onshore on IVT approaching 300
kg/m/s driving PW anomalies to above +1 sigma, highest in central
CA. This deep layer lift and anomalous moisture will lead to an
expanding area of precipitation, with upslope flow into the terrain
driving additional ascent for heavy precip rates. Snow levels are
progged to be around 5000 ft, so heavy snow accumulations are
likely above these levels, especially in the Sierra where WPC
probabilities for 4+ inches are 70-90%, and locally 8-12 inches is
possible. Additional moderate snow is likely in the
Shasta/Siskiyou region as well, where WPC probabilities for more
than 4 inches reach 30-50%.


For days 1-3, the probability of significant icing is less than 10
percent.


Weiss