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Avalanche Forecast

Apr 17th, 2013–Apr 18th, 2013
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
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: South Columbia.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Two approaching frontal systems will bring warm, wet and windy weather through the forecast period. Thursday: Overcast. Moderate precipitation amounts. Ridgetop winds moderate from the NW. Freezing levels rising to 1900 m. Friday: Overcast. Light-moderate precipitation amounts. Ridgetop winds moderate from the West. Freezing levels 1700 m. Saturday: Overcast. Light precipitation amounts. Ridgetop winds moderate to strong from the West. Freezing levels 1500 m and falling to valley bottom overnight.

Avalanche Summary

On Tuesday, a couple of large, older (past 48hrs) slab avalanches size 2-3 were spotted from the flanks of Albert Peak. Crown depths were approximately 50 cm deep and the suspect failure plane may have been the early April surface hoar. Loose wet natural avalanche activity also occurred on solar aspects up to size 1.5. In neighboring Glacier National Park, skiers triggered a size 3 slab on a buried crust on an east aspect in the alpine on Monday. Last Sunday, a naturally triggered size 2.5 slab failed on a buried crust.  With forecast snow and wind this interface may be reaching it's tipping point.

Snowpack Summary

Forecast snow and wind will likely build new wind slabs at treeline and above. Cornices are very large and pose a threat to slopes below.A weak interface down about 60-120 cm consists of a crust on solar aspects, and surface hoar on high-elevation northerly aspects. Recently, very large avalanches occurred in this region and in the neighboring Glacier National Park.  The slab above this interface may be reaching tipping point with additional loading.

Avalanche Problems

Wind Slabs

Forecast snow and wind will likely build new wind slab problems at treeline and above. Large looming cornices exist on ridgelines and pose a threat to slopes below.
Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

A weak interface buried down about 60-120 cm has been creating surprisingly large avalanches in neighboring regions. Additional loading by snow and wind may bring the slab above this layer closer to its tipping point.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1 - 6