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Avalanche Forecast

Archived

Feb 16th, 2021–Feb 17th, 2021

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Glacier.

The faceted upper snowpack is weaker than the normal conditions we enjoy at Rogers Pass. With continuing cold weather, it will not heal as quickly as one would like.

Have patience. Eventually it will warm up and dump once again.

Weather Forecast

Unsettled grey days with hints of sun and a trace of snow.

Today: Cloudy with sunny periods, Alp high -11*C, light/mod W ridge winds

Wed: Sun and cloud, Alp high -15*C, mod W winds

Thurs: Cloud and sun, Alp high -13*C, mod S winds

Fri: Cloudy, scattered flurries, 5cm, Alp high -10*C, mod S winds

Snowpack Summary

Widespread wind effect in the alpine has made for tricky travel. Large lenses of dense, hard slab are mixed with cold, cream cheese powder. The cold has weakened cornices and the upper snowpack. The January 24th weak interface, down 70-100cm, is faceting and weakening in the cold. The mid-lower snowpack is still relatively strong.

Avalanche Summary

Large natural avalanches to sz 3 were observed from the N side of Macdonald yesterday. Mac 6 ran sz 3, Mac 8, 9, 10, 11 all sz 2-2.5

Old but relevant news: a group of skiers had a close call Wed on the S face of Corbin Peak, triggering a sz 2 and a sz 3 on the Jan 24th persistent weak layer. This problem still lurks on big alpine faces.

Confidence

Problems

Wind Slabs

Wind Slab avalanches are the 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.

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.