Avalanche Forecast

Travel in avalanche terrain is not recommended on Thursday! 

On Thursday, a strong storm arrives in the early morning hours with rising snow levels and strong to very strong crest level winds with heavy rain and snow. 

Storm snowfall will be quite intense across both the west and east slopes of the Cascade with one foot or more of snow expected to accumulate during daylight hours. This snow will fall at increasing density, creating an upside down storm layers on top of the multitude of crusts and recent lower density snow already existing in the snowpack. This storm is very likely to produce a widespread natural avalanche cycle, with large avalanches in all elevations bands. 

Wind slabs forming Tuesday through Wednesday were already showing signs of significant reactivity in many areas on the crust surfaces present. On Thursday, Strong to very strong SSW crest level winds (turning westerly in the late afternoon) will quickly form very touch large to very large wind slabs on a variety of aspects, but most notably NW though SE.

Early season hazards still exist. Many creek beds have still not filled in for the winter and crusts in many areas are quite firm.

Since Sunday most east slope areas have received 6-12 inches of snow. The most recent snow has fallen with cooling temperatures but periods of very strong winds, especially Tuesday through early Wednesday. The recent storms have created sensitive wind slabs on a variety of aspects near and above treeline and on some exposed terrain below treeline. In wind sheltered terrain storm snow is low density and generally right side up. However, in some locations, storm slab formation on 1/5 and 1/9 crusts have been reactive. The supportive 1/9 crust formed from a widespread freezing rain event Thursday night and Friday in the central east slopes zone, extending to the Stevens and Snoqualmie Pass areas. 

In the northeast Cascades, no freezing rain crust exists in ski terrain along the Hwy 20 corridor nor has buried SH been discovered in avalanche terrain.

Snowdepth decreases substantially the further east of the Cascade crest one travels. In many areas below treeline, there is not enough snow to present an avalanche danger. 

Observations

North

On Monday, NCMG found  4-6 inches (10-15 cm) of lower density snowfall over a well consolidated base with little signs of recent wind transport in the Washington Pass area. No new avalanches have been observed in this area over the last two days. The 1/5 freezing rain crust found further south has not been found along the Hwy 20 corridor. 

Central

A public observation from Friday 1/5 in the Mission Ridge backcountry noted a 1/4" thick freezing rain crust up to 5000' making for treacherous travel conditions. 

Basal facets (2-3mm) observed on 1/2 above 5000' on NW-N-E aspects and failing in snowpit tests in the Blewett Pass area (and likely the Mission Ridge area) will need to be watched when enough snow returns to this area to create a potential avalanche problem.  

South

No recent observations