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Avalanche Forecast

Apr 22nd, 2012–Apr 23rd, 2012
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
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: Purcells.

Confidence

Good

Weather Forecast

Scattered cloud is forecast for Monday with the possibility of light rain in the afternoon, particularly in the north of the region. Ridgetop winds are expected to be light to moderate from the southwest with freezing levels sitting at about 3100m.

Avalanche Summary

Numerous point releases and slab avalanches to size 2.5 were observed running within the recent storm snow on Saturday. There will be ongoing to wet snow instabilities on Monday with forecast freezing levels.

Snowpack Summary

On Thursday night, light to locally moderate amounts of snow fell forming wind slabs that most likely settled considerably or turned to wet slabs with warming over the weekend. The recently fallen snow overlies well settled powder, melt-freeze crust sandwiches and wet grains. At lower elevations, warm temperatures continue to penetrate and weaken the isothermal snowpack. Deeper in the snowpack there are layers that may not be reactive with cooler temperatures, but should be on your radar as spring brings more prolonged periods of warm weather. These layers include near surface crusts, the early-February surface hoar (about 100-170cm down) and basal facets. Cornices in region are also large and will become weak with warm temperatures.

Avalanche Problems

Loose Wet

Loose wet snow avalanches are expected with continued warming on Monday. Watch for increased activity in steep, sun-exposed rocky terrain. Loose snow avalanches may entrain a great deal of mass and may trigger deeper weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely - Certain

Expected Size: 1 - 5

Wet Slabs

With continued warming on Monday, wet slabs become more likely. A number of crusts in the upper snowpack may act as a suitable sliding layer for wet slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 5

Deep Persistent Slabs

Avalanches on deep persistent weaknesses that developed earlier in the winter are unlikely, but the probability will increase as warm temperatures persist and there is no overnight freeze.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 7