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

Valid 12Z Thu Oct 30 2025 - 12Z Sun Nov 02 2025

...Washington Cascades...
Day 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 SATs.
That said, the air-mass the IVT is ushering in 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 have the better odds (WPC
probabilities >4" between 10-30%) for locally heavier snowfall
totals.


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

Mullinax