Winter is arriving slowly in the Cascade and Olympic mountains. Expect cool conditions and light snow through the weekend. You can trigger avalanches where you find strong over weak snow east of the Cascade Crest. Shallow snow cover and early season conditions exist. Watch out for open creeks, shallowly buried objects, and thinly bridged crevasses.
Look for obvious signs of instability like recent avalanches, shooting cracks, or collapses. If you witness these warning signs, avoid avalanche terrain.
Consider the consequences of an avalanche in these shallow, early season conditions. Even a small avalanche could injure you in rocky terrain.
Always carry avalanche rescue equipment when you travel in snow-covered mountains.
Snowpack and Avalanche Discussion
Since Thanksgiving, observers reported small avalanches in the upper snowpack with a series of storms that alternated between snow and rain. Avalanche activity has subsided and we do not expect a rise in avalanche danger in the next few days.
Around the Cascade Crest and the western mountains, avalanches will be unlikely or small until more significant snow accumulates. In the mountains east of the Cascade Crest, you could trigger surprising persistent slab avalanches. While observations are very limited, reports indicate that you are most likely to trigger these avalanches on shaded aspects near and above treeline.
Significant variation in snowpack structure exists throughout the region. Below treeline, snow coverage is minimal to non-existent. Near and above treeline, there is enough snow for backcountry travel and avalanches. Observations from Washington Pass, the Mt Baker area, and Mt Rainier indicate average snowpack heights of 2-3 feet near and above treeline. West of the Cascade Crest, rain fell at least up to 7500ft melting much of the low elevation snowpack. In these regions, you can find a relatively uniform snowpack punctuated by crusts in some locations. East of the Cascade Crest, weaker faceted layers with an overlying slab have been found on shaded aspects areas near and above treeline. In these areas, observers have reported collapses and snowpack tests indicating propagation.
NWAC will begin issuing daily avalanche advisories once winter is established. We are monitoring snow, weather, and avalanche conditions and will update this snow and avalanche outlook as needed.