Heavy Snow — East Slopes Northern Cascades, Washington

2020-12-20 to 2020-12-21 · East Slopes Northern Cascades, Washington

Event narrative

A member of the public, in Mazama, reported 9.0 inches of new snow accumulation.

Wider weather episode

A new winter system moved in as a trough dropped into the Pacific Northwest on December 21st. With the accompanying atmospheric river, this system had substantial moisture with it bringing a wet and windy day ahead. Most of Eastern Washington was still too warm for snow, but there was moderate snowfall in the east Cascade slopes. Throughout the remainder of the region, locations received 24 hour rainfall totals up to 0.5 - 1.0.

In addition to wet conditions, the evening of the 21st into the early morning hours of the 22nd were windy, with damaging winds in the Palouse. The strongest winds were in far Eastern Washington, from Spokane to Pullman, and Cascade slopes. There were sustained winds 20 - 30 mph with gusts to 35 - 50 mph for over a 12 hour period. It was windy for much of the region, but much lighter with gusts to approximately 20 mph. Numerous power outages occurred in Chelan, Whitman, and Stevens counties.

Source: NOAA Storm Events Database, event_id 933514. Narrative written by the NWS forecast office that issued the report.