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RegisterJan 21st, 2018–Jan 22nd, 2018
Stevens Pass.
Avalanche danger will generally decrease during a break from the active weather Monday. While avalanches will become increasingly difficult to trigger, resulting avalanches may entrain significant snow, causing them to grow larger than expected. Ease into terrain Monday. Identify and avoid slopes where avalanches are more likely to trigger.
A relative break in the weather Monday will allow avalanche hazard to decrease slightly in most areas. Isolated locations may experience higher precipitation rates in the morning hours and in convergence north of Stevens Pass.
Wind slabs formed throughout the storm period will continue to linger along ridge lines and crossloaded features near and above treeline. Stronger winds in the southern part of the region may have produced wind loading father down slope than expected. Identify and avoid areas of wind deposited snow such as below cornices, wind drifts, and crossloaded slopes.
Storm slabs layers will continue to gain strength. Identify and avoid areas were storm slabs are more likely to trigger such as steeper slopes, convex rolls, and unsupported slopes.
Avalanches may entrain significant new snow allowing them to grow larger than expected. Select terrain wisely and minimize exposure of your group to avalanche paths above you.
An active weather pattern Wednesday through Sunday deposited 12-18 inches of settled snow over the most recent crust layer. Observations show the recent snow is generally well bonded to the old snow surface.
Fluctuations in temperature and precipitation intensity created several layers within the upper snowpack during the day Sunday. These firmer layers lie above very soft snow from Saturday.
Winds, particularly at Paradise and Crystal, transported snow forming wind slabs in exposed terrain near and above treeline.
Observations
Central
An avalanche professional in the Stevens Pass area Sunday reported 18 inches of generally right-side-up snow well bonded to the 1/16 crust. No avalanches were observed.
An avalanche professional in the Snoqualmie Pass area Sunday reported 12 inches of snow well bonded to the 1/16 crust. They observed wind transportation of snow above 4000 feet. Several natural, small and isolated wind slab avalanches were seen in very steep northerly terrain.
A public observation from Jim Hill on Saturday reported an avalanche triggered by cornice fall on a near treeline N-facing slope.
NWAC Pro Observer Jeremy Allyn was in the Snoqualmie Pass area Friday and Saturday. On Saturday Jeremy observed 18 inches of recent snow over the 1/16 crust layer. Wind transportation was limited to exposed ridgeline terrain features. No new avalanches were observed.
South
On Friday, NWAC forecaster Dallas Glass traveled in the Crystal Mountain backcountry. The recent winds have caused highly variable storm snow conditions with exposed areas striped of recent snow. New snow was observed to be generally well bonded to the most recent crust.
Pro Patrol at Crystal Mountain Thursday morning reported shallow 2-4" very soft slabs. The underlying rain crusts have become very firm by Thursday morning above 6000 ft and gradually softer at lower elevations.