Avalanche Forecast

Warming air temperatures, more precipitation, and increasing winds will develop very dangerous avalanche conditions Saturday morning. Expect natural avalanches to occur around periods of increased precipitation and significant warming.

Very large and destructive avalanches may occur Saturday entraining significant amounts of snow and traveling far into runout areas. Avoid traveling in areas where avalanches may start, run, and stop. Traditional travel locations may be impacted by larger avalanche starting at higher elevations. Identify and avoid traveling in areas steep open slopes overhead.

This is a time for very conservative terrain use. If you choose to travel in the backcountry utilize lower angle terrain well away from avalanche paths. Remember large terrain can produce large avalanches.

Cornices during this storm cycle have grown quite large. Give them a wide berth as they may break much farther back from the ridge than you might expect.

Snow conditions have changed significantly during this storm cycle. Tree-well and snow immersion hazards are very dangerous. Maintain communication with your partner at all times.

A very active storm cycle over the past nine days deposited significant amounts of snow along the west slopes of the Cascades and in the Passes. In most locations 2 to 3 feet of settled snow sits on top of the most recent crust layer.

Several subtle storm weaklayers can be found. Depth and sensitivity of theses layers varies with location. Observations demonstrate storm snow weaknesses gaining strength. Widespread loose surface snow conditions were reported in most areas.

Winds redistributed storm snow near and above treeline. This was most notable in the Crystal backcountry where much of the terrain was reshaped by strong SW winds.

Poor visibility and frequent storm has limited observations above treeline.

Observations

Central

Avalanche professionals in the Stevens Pass and Snoqualmie Pass areas Friday found very touchy 6-12 inch storm slabs in open terrain. Wind transportation of snow was localized to exposed ridges and upper elevations near and above treeline.

On Thursday morning, NWAC staff in the Alpental valley observed debris from a very large natural avalanche that released from Chair Peak. This avalanche likely occurred sometime Wednesday into early Thursday morning. The debris crossed Source Lake and extended far into the runout.  

Ski Patrollers at the closed Alpental ski area reported a large skier triggered slab avalanche 20" deep releasing in Powder Bowl. Fresh large cornices have built along ridgelines in this area.

South

NWAC Observer Jeremy Allyn was in the Crystal area Friday. He observed wind redistribution of snow forming wind slabs on lee slopes near treeline. In sheltered areas, Jeremy found soft snow conditions, with 3 feet of storm snow over the most recent crust layer.

NWAC forecasters in the Crystal backcountry on Thursday reported 1 to 2 feet of storm snow well bonded to the 1/16 crust. The new snow generally had a right-side up profile with recent storm instabilities healing. Occasional gusty winds transported recent snow near and below ridgeline.