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Avalanche Forecast

Archived

Feb 2nd, 2014–Feb 3rd, 2014

Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Coastal.

Confidence

Good

Weather Forecast

Tonight and Monday: An arctic ridge is building and is there to stay for a little while. Expect mainly sunny skies, moderate to strong NE winds, and cold tempreratures (-15 C in the alpine).Tuesday: The ridge is gaining more strength spreading more dry and cold weather. Moderate NE winds, partly cloudy skies, alpine temperatures around -18 C.Wednesday: More of the same. Mainly clear skies, cold temperatures but winds should diminish to lighter speeds from the N.

Avalanche Summary

Multiple skier triggered slab avalanches size 1 in the alpine were reported yesterday.

Snowpack Summary

The 5-10 cm of recent snow has been redistributed by N and recently by SE winds creating pockets of relatively thin windslabs on immediate lee features in the alpine and at treeline. These windslabs are sitting on weak surfaces like a crust or on the late January surface hoar layer. It has been reported that they are reactive to skier traffic. A well settled mid and lower snowpack is resting on basal facets, which is a concern especially in thin snowpack areas at higher elevations. At the surface of the snowpack, there is widespread growth of surface hoar and surface facetting that will continue with the forecasted clear and cold temperatures.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.