Subj : HVYSNOW: Probabilistic Heavy Snow And Icing Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Oct 30 2025 20:14:41

FOUS11 KWBC 302014
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
414 PM EDT Thu Oct 30 2025

Valid 00Z Fri Oct 31 2025 - 00Z Mon Nov 03 2025

....Washington Cascades...
Days 2-3...

A shortwave disturbance at the base of a massive longwave trough
positioned over the northeast Pacific will direct a highly
anomalous IVT topping 1,000 kg/m/s at the Pacific Northwest late
Friday night and into Saturday. There is no shortage of moisture
within the IVT as PWs approach 1.25" over western WA, which in some
instances tops the 99th climatological percentile per ECMWF and
NAEFS SATs. That said, the Pacific air-mass is also rather mild
and antecedent boundary layer temperatures are not cold enough to
support heavy snowfall below 5,000ft south of US Route 2 and
Stevens Pass. Most passes should remain below the freezing level,
making rain the primary precipitation type below 5,000ft. The
Cascades north of US-2 above 5,000ft maintain better odds for
locally heavy snowfall, where localized 50-80% probabilities of
exceeding 4 inches are noted this forecast cycle.


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

Asherman/Mullinax

















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