Avalanche Forecast

Strong alpine winds and moderate to heavy rain and snow will accompany a cold front across the Northwest Saturday afternoon to Sunday morning. This should bring 1-2 feet of new snow near and above treeline with a warming trend which greatly increases the likelihood of storm and wind slab layers.

Back country early season conditions are changing fast! New potentially large storm and wind slab will be the focus on Sunday especially in the Mt Baker area but also along the entire west slopes. Human triggered storm slab should be likely to very likely on varied aspects. Human triggered wind slab should be likely to very likely mainly on lee north to east slopes especially above treeline. Back country travel is not recommended Sunday near and above treeline.

The next strong system should begin to move into the Olympics and Cascades Sunday night. But be prepared to curtail your plans later Sunday if conditions deteriorate sooner than expected.

Recent observations have identified a persistent weak layers in the Stevens Pass area. We don't know anything about this layer yet in the Snoqualmie Pass area. We don't deal with PWL layers very often near and west of the crest so we need to use extra caution in the Stevens and Snoqualmie Pass areas until more information is obtained. Stay on low angle slopes and watch and listen for clues like cracking and whomping.

Early season hazards exist for much of the below treeline band throughout the Northwest, so ski and ride with caution. 

We had a wild and wet month of November, with 12- 25 inches of water at west side NWAC stations only amounting to about a 1 meter or 3 foot snowpack in the north Cascades above 4000 feet and above 6000 feet elsewhere. Then strong high pressure led to strong temperature inversions and brought very cold air through the Cascade Passes over Thanksgiving weekend. The weather pattern has become more active for the first few days of December with a few inches of new snow over the west slopes paired with moderating temperatures in the Passes. 

Snowpack and Avalanche Observations: Minor activity along the west slopes away from the Cascade Passes last week was confined to new storm snow.

Update Sunday morning: New NWAC pro-observer Simon Trautman was near the Mt Baker Ski Area on Saturday and reported reactive upside down P hardness wind slab over lower density layers with numerous natural storm slab avalanches and some remote ski triggered storm slab avalanches up to about 15 inches. The avalanche danger forecast for the west slopes of the Washington Cascades has been nudged up due due to this new information.

The west slopes do not have a uniform maritime snowpack! Due to the cold temperatures and clear skies near the end of November, buried surface hoar can be found in the Stevens Pass area. NWAC pro-observer Dallas Glass found this layer at 4-5000 feet at Skyline on E-NE aspects around 45 cm down. Faceting may also be found at a similar depth on solar aspects around a buried sun crust.  Stevens pass pro patrol reported a 12-14 inch (30-35 cm) natural persistent slab avalanche in closed Corona Bowl of the ski area Friday on a N-NW aspect.  Professionals also reported shooting cracks and whumpfing in the area as temperatures warmed and the slab above the PWL became cohesive.