Avalanche Forecast

A frontal system should take aim mainly at the north Cascades Saturday, with light precipitation beginning for the Cascade Passes around mid-morning. Cool easterly pass flow should mitigate a slow warming trend found elsewhere along the west slopes. 

Recent observations have identified a reactive persistent weak layer in the Stevens Pass area.  We don't know anything about this layer in the Snoqualmie area, but recent weather/snowpack conditions were similar to those found in the Stevens Pass area. 

This is a dangerous setup heading into the weekend! Persistent slabs are likely to be human triggered in open areas near treeline where the persistent weak layer was buried intact. While the slabs above the PWL are not massive, we don't deal with this particular avalanche problem very often in a maritime snowpack and need to use caution until more information is obtained.

Stay on low angled slopes and watch and listen for obvious clues like shooting cracks and whumpfing.

Older wind slabs formed late last month and earlier in the week may be found on westerly aspects near and above treeline. Shallow storm slabs are possible on all aspects by later in the day Saturday, but will not be listed as a primary avalanche problem.  

Early season hazards exist for much of the below tree-line 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 (~3 ft) snowpack in the north Cascades above 4000 ft and above 6000 feet elsewhere. Strong high pressure led to steep 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. 

Avalanche and snowpack observations: Recent activity along the west slopes away from the Cascade Passes has been confined to new storm snow. New NWAC pro-observer Lee Lazzara noted a natural cycle of loose wet avalanches on Wednesday as temperatures warmed. This natural cycle likely extended to higher elevations in the north Cascades on Thursday as rain pushed above 5000'. Mt. Baker and Crystal patrols reported small avalanches involving new storm snow during control work Fri AM.   

The west slopes do not have a uniform maritime snowpack! Due to 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 around 5000' in the Skyline area on E-NE aspects around 45 cm down. Faceting may also be found on solar aspects around a buried sun crust. Stevens pass pro patrol reported a 12-14" (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.

We still have many gaps in our observation network as it's early season, so make your own observations and use them in co-junction to our regional avalanche forecast. Thanks for reading the first NWAC avalanche forecast for 2015-16 season, stay safe and have fun!