Avalanche Forecast

Issued: Nov 26th, 2015 8:33AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Deep Persistent Slabs.

bcorrigan, Avalanche Canada

South Columbia.

Rising alpine temperatures up to +5c are in the forecast for the next few days. Use care venturing into big terrain at treeline and above. Consider sharing your observations through the Mountain Information Network MIN

Summary

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

Arctic air has moved in from the north bringing clear skies and cooler than average temperatures.Â Strong northerly winds at ridge top are beginning to moderate. Above freezing temperatures between 1500 and 3000m are forecast to begin Friday morning and continue into the weekend, but valley bottoms will remain well below freezing with valley fog in the morning dissipating by afternoon in most places.

Avalanche Summary

Explosive control by one operator produced a number of 2.5 size avalanches. A skier triggered avalanche at 200m on a SW aspect was also reported a few days ago. No reports of avalanche activity from yesterday.

Snowpack Summary

Monday's storm snow fell on a variety of old surfaces including crust, surface hoar and old settled snow. Arctic air moving into the region has resulted in northerly winds forming small wind slabs on south facing features near ridge top and t tree line. Warm temps and strong solar input formed a crust on south facing features which can be found underneath Monday's storm snow. There are at least three surface hoar layers in the snowpack buried on: Nov. 5th, Nov. 11th and Nov. 23rd. The first two have been largely unreactive. Facets may exist just above the ground on shaded slopes in the alpine. Rapid rising temperatures forecast for the next few days may change the snowpack dramatically.

Problems

Wind Slabs

Strong winds from the north in the past few days have redistributed storm snow over surface hoar on shaded aspects and may be hiding sun crust on solar aspects.

Avoid freshly wind loaded features.>Stay well to the windward side of corniced ridges.>Be cautious as you transition into wind affected terrain.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

Snow from early in the season has become facetted and weak at the base of the snowpack, mostly on northerly aspects

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Sluffs may trigger deeper instabilities.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 5

Valid until: Nov 27th, 2015 2:00PM