Avalanche Forecast

Additional snow and wind will cause the avalanche danger to increase Friday creating dangerous avalanche conditions in most locations. Wind and storm slabs will grow larger and easier to trigger as the day passes.

You will be able to trigger wind slabs on exposed terrain near and above treeline. Moderate to strong westerly winds will transport snow forming new and sensitive wind slabs. Identify and avoid areas of wind deposited snow. Visual clues such as blowing snow, plumes, and fresh cornices all indicate wind slabs are present on slopes below.

Storm slab avalanches will be found on all aspects and elevations in steep sheltered terrain. Warming air temperatures, higher density snow, and additional precipitation will cause storm slabs to become easier to trigger. Avoid open slopes above 35 degrees where you will be able to trigger an avalanche.

At lower elevations, especially around Snoqualmie Pass, snow will transition to rain late in the afternoon. If you receive rain, expect loose wet avalanches on all steep slopes. Stay off of terrain where being caught in even a small avalanche could have large consequences.

Around the west slopes of the Cascades 8-12 inches of storm snow fell Valentine’s Day. In most locations reports showed soft weak surface snow conditions with small loose dry avalanches reported Wednesday and Thursday. Locally at Snoqualmie Pass the new snow formed shallow cohesive slabs resulting in one snowboarder triggered avalanche and numerous natural storm slab avalanches.

This recent snow fell on a variety of snow surfaces including firm melt-freeze crust, wind affected snow, and weak near surface facets. The bonding of the new snow to the old snow surface was improving Thursday.

Unstable snow has been isolated to the recent storm snow and its bonding to the most recent crust. Warm wet weather during early February has created a strong consolidated mid and lower snowpack. Although we are tracking older buried crust, there are currently no significant layers of concern.

Observations

NWAC staff in the field Wednesday and Thursday in the Stevens and Crystal Mt backcountry areas found loose surface snow conditions resulting in numerous loose dry skier triggered avalanches. Wind transported snow was seen to be isolated to exposed features near and above treeline.

At Snoqualmie Pass, NWAC staff and Alpental ski patrol reported natural storm slab avalanches from Wednesday. While this storm snow weakness was still evident, observations demonstrated it was gaining strength.