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Archived

Avalanche Forecast

Feb 20th, 2013–Feb 21st, 2013
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
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Cariboos.

Confidence

Good

Weather Forecast

Synopsis: A series of frontal systems is expected to affect the region over the next few days bringing steady moderate precipitation and seasonal temperatures.  Thursday: Light to moderate snowfall – 5-10 cm. Winds are moderate and gusty from the west-southwest. The freezing level is around 900 m. Friday: Moderate to locally heavy snowfall – 20-30 cm. Winds are strong from the southwest and the freezing level is around 700 m. Saturday: Cloudy with flurries or light snow. The freezing level is steady at 700 m and winds ease to light from the northwest.

Avalanche Summary

A new size 2.5 natural avalanche was reported on the east side of the region. This event occurred on a south aspect in the alpine and likely failed on a sun crust, down approximately 40 cm.

Snowpack Summary

Variable amounts of new snow continue to add to the recent storm slab which sits above the February 12th weak surface hoar layer and a sun crust on solar aspects. This layer is now buried down about 30-60 cm deep depending on where you are in the region. New wind slabs developed at treeline and above due to the new snow and wind during the storm. These soft new wind slabs (hard slabs in some areas) are reported to be reactive and may be hiding stiffer wind slabs that are a couple of days older. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied in snow pack tests. These deeper layers have not been reactive to the weight of a rider, but they may be triggered by large loads like an avalanche in motion, or a cornice fall.

Avalanche Problems

Wind Slabs

Fresh wind slabs may form on exposed north through east aspects near ridge tops and behind terrain features. These could be triggered by the weight of a rider.
Be cautious as you transition into wind affected terrain.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 5

Persistent Slabs

Up to 40 cm of settled storm snow sits on the Feb. 12 surface hoar or sun crust. Additional loading from snow and wind or the weight of a person could be enough to trigger this weak layer.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 5