Avalanche Forecast

On Monday, sun and increasing temperatures drove small loose wet avalanches on steep sunny slopes. Many of the natural avalanches that were observed appeared to originate from chunks of falling snow near cornices, trees, or rocks. Observers also reported surface hoar persisting on the surface of many shaded slopes.

Tuesday will bring a slight rise in temperatures and increasing clouds skies with light precipitation and westerly wind beginning in the late afternoon. Where enough sun shines on Tuesday morning, there's a chance that you may still encounter small loose wet avalanches on steep sunny slopes. Use caution near terrain traps where these avalanches could be dangerous. Large cornices loom on most high ridges from many westerly wind events this winter. Use caution to not travel on or under overhung cornices.

Small loose wet avalanches on an east aspect near 4,400ft on Skyline Ridge, Stevens Pass. 3/9/2020. Photo: Josh Hirshberg

March 5, 2020 (The regional synopsis is updated every Thursday @ 6 pm)

 

Ridgetop wind transport near Washington Pass. 3/4/20 Photo: Josh Hirshberg

 

The beginning of March brought the first spring-like weather to the region. The days are getting longer and the sun (when it shines) has a noticeable effect on the snow. Alternating sun breaks and snowstorms is the theme of the week and the avalanche danger fluctuated just as fast as the weather. The southern zones and the east slopes have seen periods of light snowfall and significant sunshine while the northern zones and west slopes have had significant snowfall and occasional sun breaks. Above freezing temperatures were common at lower elevations throughout the region. 

Last week in review:  Temperatures were above freezing at most trailhead locations and concerns about the previous week’s buried surface hoar and weak layers were fading. Saturday temperatures plummeted as strong winds and new snow built wind slabs in most areas and drove the avalanche danger to considerable in almost every zone. Sunday’s calm weather and clearing in most areas helped stabilize wind slabs, but our attention turned to the strength of the sun and daytime warming. Lingering wind slabs and loose wet avalanches were forecast in every zone. For the remainder of the week, the avalanche problems in every zone were confined to the recent snow and each brief storm cycle had us thinking about wind slabs at upper elevations and loose wet avalanches from daytime warming and sunshine.

Spring isn’t actually here -- another round of cold temps and snow showers are on the way this weekend, but this past week’s oscillating weather is a good reminder to begin to shift our mindset. The sun is gaining strength, the days are getting longer, and we begin daylight savings this week. Even a brief period of sunshine can dramatically alter fresh, new snow. Check the mountain weather and avalanche forecasts for the most up to date info, enjoy the backcountry and let us know what you see out there!

--Peter Moore

Wet loose avalanche debris near Snow Lake. 3/5/20 Photo: Dallas Glass

Fresh cornice development from strong winds in the Stevens Pass backcountry. 3/4/20 Photo: Tom Whipple