Avalanche Forecast
Regions: Olympics.
The Bottom Line: Snow conditions and stability will still vary a lot depending on location on Saturday. It would be wise to choose safer terrain if you are uncertain of stability.
Detailed Forecast
Mostly cloudy cool weather with a slight chance of light snow showers should be seen in the Olympics, west of the crest and on the volcanoes on Saturday. Little if any snow accumulation is expected.
Layers and snow from the recent storm should slightly stabilize on Saturday.
Decreasing areas of wind slab from the recent storm may linger on lee slopes above tree line on Saturday. Watch for signs of wind transported snow above treeline.
Temporary but decreasing areas of storm slab may survive until Saturday on sheltered slopes near and below tree line.
Be sure to read avalanche forecasts for Stevens and Snoqualmie and east of the crest if you plan to visit those areas. Remember that there could be a very sharp difference in snow stability over relatively short distances across the Cascade crest for example in the vicinity of Crystal Mountain.
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Snowpack Discussion
Heads up folks because the avalanche picture has greatly changed in the Washington Cascades from the past couple weeks.
NWAC sites in the Olympics, west of the crest and on the volcanoes indicate about 1/2-3 feet of snowfall for the 3 days ending Friday from the recent storm. This is expected to have built new wind slab on lee slopes above tree line and new temporary storm slab on sheltered slopes near and below tree line. These should be the most important concerns in the Olympics, west of the crest and on the volcanoes.
The Mt Baker ski patrol reports that several skiers triggered storm slab avalanches of 6-12 inches on Shuksan Arm today with the largest about 200 feet wide. Fortunately so far there have been no injuries or burials.
The mid and lower snowpack in the Olympics, west of the crest and on the volcanoes consists mainly of crusts and melt form crystal layers which have generally not been reactive to to snow pit tests. Low snow amounts are limiting the avalanche danger on many south slopes and at low elevations due to terrain and vegetation anchors.
Note that dangerous persistent large hoar frost that formed during the latter part of the recent 2 week fair weather period at Stevens and Snoqualmie and east of the crest has been buried in those areas. Be sure to read avalanche forecasts for Stevens and Snoqualmie and east of the crest if you plan to visit those areas. Remember that there could be a very sharp difference in snow stability over relatively short distances across the Cascade crest for example in the vicinity of Crystal Mountain.
Avalanche Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Elevations: Treeline, Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1