Avalanche Forecast

Archived

Feb 10th, 2019–Feb 11th, 2019

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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This storm pattern has been unusual, and will continue to produce low density snow along with instabilities for Monday. We are tracking a recently buried persistent weak layer that has been found on a variety of aspects. This layer may produce wide avalanches and they may triggered from a distance. Seek out slopes less than 33 degrees if you find slab structure over facets.

Discussion

Snow and Avalanche Discussion

A series of strong and cold storms continue to roll through, mainly to the south of the area. On Sunday, a single D2 avalanche was reported from the Baker area at 5,200ft on a steep Southwest aspect. It was triggered remotely by a skier. Investigated by a pro observer, it was found to have failed on a layer of facets above a thin suncrust. An observer reported instabilities on a similar layer on southerly aspects near Washington Pass on Saturday. Nearly a foot of new snow may often lack cohesion, or a slab structure. Areas of wind slab are more likely to have formed closer to Washington Pass, where winds funneled through and sped up.

Most avalanche accidents occur with Considerable Danger. As the snow continues to lightly pile up, continue to be aware of your surroundings and check for instabilities. Ask yourself, "Am I in avalanche terrain? Could the snow slide?" Traveling one at a time is good practice, but it does not eliminate the hazard of choosing to enter avalanche terrain. Slopes of less than 30 degrees, and places well away from steep open slopes would be my preferred terrain choice.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.