FOUS11 KWBC 280846
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
446 AM EDT Wed Oct 28 2026

Valid 12Z Wed Oct 28 2026 - 12Z Sat Oct 31 2026


...Northern Cascades and Northern Rockies...
Day 1...

A low pressure system shifting south across Vancouver Island today
continues to promote heavy snow over the WA and northern OR
Cascades into this evening. The ample moisture streams inland as
well, bringing heavy snow to terrain in northern Idaho and
northwest Montana through tonight. The low stalls just off western
Washington into Saturday with a combo of mostly dry slot and brief
shortwave trough activity over the Northwest through that time.  

Snow levels are at or below Washington Cascades passes today,
generally around 3500ft and 4500ft down through the central Oregon
Cascades. The heaviest rates are early this morning as inferred by
regional NEXRAD depicting bright banded areas of precip pushing
east of Seattle to Portland as of 0830Z. Both the 00Z HREF and 06Z SPC
REFS depictions of mean snowfall rates support 1-2"/hr rates until
about 16Z when mean rates dip to 1"/hr or less on the higher
Cascades. Day 1 WPC snow probs for >6" are 30-80% above pass level
with 20-40% probs for >4" at pass level in the Washington Cascades. 

The heaviest snow rates occur on the far northern Rockies 
(generally north from the Bitterroots) today from around 16Z to 22Z
per both the recent HREF and REFS mean snowfall rate products with
rates generally 0.5 to 1.5"/hr. Day 1 WPC snow probs for >6" are
40-80% in this terrain above the snow levels around 4500ft. 

As noted above, shortwave activity should product additional snows
over these areas into Saturday. The Day 2.5 snow probs for >4" are
20-40% in the North Washington Cascades where snow levels should be
around 3000ft.


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


Jackson



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