Avalanche Forecast

NWAC and NPS staff in at Hurricane Ridge on Thursday experienced variable firm and breakable crusts with some patchy wind deposits on many aspects, while NW-N-NE aspects above 4500 ft held 4-6" of dense, settled dry snow above a firm crust. There were areas of wind-affected snow, and wind lips, but no wind slabs.

Avalanche concerns are limited to the new snow. Your danger Friday depends upon how much snow falls Thursday night. If we get 6” or more of new snow, prepare to dial back your terrain selection and avoid unsupported lee slopes steeper than 35 degrees. With the 4-5” expected by Friday morning, you’ll need to watch for isolated areas of wind-deposited snow deeper than 6” where you can trigger a small avalanche. 

The storm arrives with decreasing winds and decreasing temperatures, which should help the stability profile and the snow bond to the old snow interface. Keep your eyes out for areas that don’t match this forecast, where winds created punchy layers in the snow, or where the snow hasn’t bonded well to the underlying crust.  

Very small loose wet avalanches should be avoided, particularly where they might push you over a cliff or into a gully.

There are still some large cornices out there, so avoid lingering on the slopes below.

Forecast Schedule

For the 2019-20 winter season, avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week, No Rating will be issued but forecasts will include expected conditions and relevant travel advice.  If you are out in the Olympics, share your backcountry observations.

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