Avalanche Forecast
Regions: Cascades - North West.
Watch for wind slab on lee slopes near and above treeline especially due to more loading on southerly aspects than usual. Loose sluffs should be manageable except be wary on steeper slopes near terrain traps.
Detailed Forecast
Isolated snow showers, increasing high clouds, light W-NW winds and cool temperatures should do little to change the avalanche danger Friday. Watch for wind slab on lee slopes near and above treeline. NW winds have likely loaded southerly aspects more than usual. Loose sluffs should be manageable except be wary on steeper slopes near terrain traps.Â
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Snowpack Discussion
The frontal system that impacted the area Tuesday through Wednesday morning started warm and ended cold for a right side up layering. New snowfall generally ranged 6-12", with lower amounts near Snoqualmie.  Winds turned northwesterly with the cool-down... loading SE aspects Wednesday. A few inches of new snow accumulated Wednesday night and Thursday.Â
On Wednesday, NWAC Pro-observer Jeff Hambelton in Mt. Baker area found a right-side upper snowpack. Moderate wind transport had created a stiffer layer of snow on some lee slopes near and above treeline and observed small loose dry sluffs - Watch Jeff's video. Â
Moderate NW winds and light snow showers on Thursday continued to load lee slopes.Â
The lower snowpack is generally strong and comprised of crusts and polycrystals. Â
If traveling to the east slopes of the Cascades be aware of the different snowpack structure containing persistent weak layers and read the avalanche forecast.Â
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, South.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
Loose Dry
Release of dry unconsolidated snow. These avalanches typically occur within layers of soft snow near the surface of the snowpack. Loose Dry avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs. Loose Dry avalanches can trigger slab avalanches that break into deeper snow layers.
Loose Dry avalanches are usually relatively harmless to people. They can be hazardous if you are caught and carried into or over a terrain trap (e.g. gully, rocks, dense timber, cliff, crevasse) or down a long slope. Avoid traveling in or above terrain traps when Loose Dry avalanches are likely.
Loose Dry avalanche with the characteristic point initiation and fan shape.
Loose dry avalanches exist throughout the terrain, release at or below the trigger point, and can run in densely-treed areas. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1