Avalanche Forecast

Light snowfall accumulations are expected Friday night through Saturday above 3500 feet along the west slopes.

Moderate W-SW winds will transport new snow onto lee slopes near and above treeline. New snow is generally expected to bond well to moist snow surfaces and various crusts, but wind-driven snow may build unstable wind slab on lee aspects. 

Wet loose avalanches may still be locally a concern on steeper slopes at lower elevations, especially in areas that received heavier rainfall Thursday night and Friday like in the vicinity of Mt. Baker and Mt. Rainier but loose wet will not be listed as a primary avalanche problem. 

Avoid cornices along ridges and slopes below cornices since cornices may still be weaker due to the warm weather.

Glide avalanches occur when a smooth bed surface (ex.rock face) becomes lubricated by water and the wet slab above releases. They are not tied to specific air temperature or rainfall trends other than they occur during or after prolonged mild conditions, similar to what we have experienced over the last several days. Be aware that even with lower snow levels Saturday, isolated but powerful glide avalanches are possible in the right terrain features until we have an extended period of cold weather.   

The avalanche danger will increase rapidly Saturday night as snowfall increases along with a slow warming trend. This unstable combination of moderate to heavy precipitation and warming may continue on Sunday leading to high avalanche danger in many areas.

Weather and Snowpack

A large upper ridge and warm air mass aloft over the West Coast from this past Sunday through Wednesday led to the warmest weather of the winter. During this stretch temperatures were generally well above freezing. A warm front brought periods of rain to the west slopes Thursday night through mid-day Friday, with snow levels falling to 5000 ft after the frontal passage Friday afternoon. 

The warm temperatures and solar effects earlier in the week caused loose wet avalanches and overall snowpack consolidation while recent rainfall has kept the upper snowpack moist in many areas. The upper snowpack should be well bonded to the 1/28 rain crust in all areas along the west slopes. 

Recent Observations

NWAC pro-observer Ian Nicholson was in the Snoqualmie Pass backcountry on Tuesday and reported that an extensive loose wet avalanche cycle with some large avalanches had occurred on Monday. In the same area, only a few small natural loose wet avalanches were seen on Tuesday. 

Another sign of the ongoing warmth, both the Alpental and Mt. Baker pro-patrol reported glide cracks with small glide avalanches releasing off of steeper rock faces within their respective areas Thursday. Mt. Baker pro-patrol reported additional small glide avalanches Friday.