Avalanche Forecast

Another round of light snow showers, except locally moderate closer to the Cascade crest Friday night should be followed by increasing shower activity late Saturday afternoon and evening. Look for a relative break in precipitation from Saturday mid-morning through early afternoon. The slow warming trend seen along the east slopes should accelerate a bit on Saturday as arctic air currently in place is continuously eroded by westerly flow.   

Dangerous avalanche conditions may develop on Saturday as we look to tip the scales with additional light loading particularly in the Washington Pass area. Gradual warming will help new snowfall settle and develop more of a slab structure. Slabs may fail on weak persistent grain types formed prior to this storm cycle. There is a large amount of uncertainty so it's imperative you assess snowpack stability throughout the day throughout the terrain and quickly dial back your plans if you experience signs of increasing instability.

Look for new wind slab near and above treeline particularly in the Mission Ridge area where the greatest danger will be on lee easterly aspects. The avalanche forecast will reflect a greater likelihood of a wind slab problem in the central-east and southeast zones than the Washington Pass area. Due to ongoing easterly winds closer to the Cascade Passes, wind slab will be listed on all aspects.  

In steep sheltered terrain continue to watch for small loose dry avalanches near terrain traps like cliff bands where even small avalanches can have big consequences. 

Even though the lower part of the below treeline band is filling in, watch for early season travel hazards such as barely covered rocks and open creeks.

Weather and Snowpack

An active and cool weather pattern has resulted in a snowy December thus far with NWAC stations along the east slopes recording about 1-2 feet of snow.

Cold and fair weather took hold midweek. During this time, there have been many reports of right side up, favorable density profiles with lower density snow nearer the surface. The Washington Pass area in particular has enjoyed excellent skiing and riding conditions with good stability and light winds. Widespread near-surface faceting and surface hoar formation had been observed particularly in this area of the east slopes. The Mission Ridge area experienced moderate easterly winds through Thursday night before switching to moderate westerly winds early Friday morning. Generally light snowfall accumulated Thursday night and Friday along the east slopes. 

Recent Observations

Pro-observer Jeff Ward was in the Washington Pass area Friday and reported up to 25 cm (10") of new snowfall at Pass level by Friday afternoon. The new snow was of lower density but cohesive enough that easily and remotely triggered soft slabs were possible on all aspects with rapidly decreasing stability.

Mission Ridge pro-patrol reported the switch to westerly winds had loaded NE aspects below ridgetop. Easy to trigger wind slabs of 40 cm deep were observed on NE aspects around 6700 feet. Just a few hundred feet below in less wind affected terrain, the snowpack was generally right side up and lacked a cohesive slab. A shallow snowpack still locally limits the avalanche danger to the higher elevations and more wind loaded aspects.