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Avalanche Forecast

Feb 28th, 2017–Mar 1st, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Strong winds and new storm snow are driving the danger ratings. Fresh and reactive slab will likely build through the forecast period.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Wednesday: Snow accumulations 5-10 cm with moderate-strong SW winds. Alpine temperatures high of -6.Thursday: Snow 10-20 cm with strong SW winds. Alpine high of -3 and freezing levels 600 m. Friday: Mostly cloudy with possible sunny breaks. Snow amounts 5-10 cm and light-moderate ridgetop winds from the SW.

Avalanche Summary

On Monday, several natural wind slab avalanches were reported up to size 1 above 1300 m. A cornice also failed size 2 and did not pull a slab avalanche from the slope below. Changing wind directions and new storm snow will likely develop new wind slabs at upper elevations.

Snowpack Summary

Recent storm snow 10-20 cm has fallen and buried a new surface hoar layer. Im uncertain of how well preserved this layer is and if it is widespread. The new snow has also buried a variety of old surface conditions including isolated wind slabs, sun crusts, and facetted snow. At lower elevations (below 1000 m) a supportive rain crust exists. Deeper in the snowpack 30-60 cm down a layer of surface hoar was buried on February 10th at tree line elevations and continues to be reactive in some recent snowpack tests. Below this layer, the snowpack is generally settled and strong. The exception is shallow snowpack areas around Bear Pass and Ningunsaw where basal facets remain an ongoing concern.

Avalanche Problems

Storm Slabs

Fresh storm slabs will likely be more reactive on leeward slopes that see deeper deposits due to wind loading, or where they overlie buried surface hoar.
Minimize exposure to avalanche terrain during periods of heavy loading from new snow, wind, or rain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2