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Avalanche Forecast

Feb 28th, 2013–Mar 1st, 2013
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Purcells.

There seems to be a high uncertainty with precipitation amounts for the region with an approaching Pineapple Express. However what is more certain is the region will be affected by strong winds and relatively high freezing levels.

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain on Friday

Weather Forecast

Friday: Thursday night into Friday a warm front associated with a Pineapple Express weather system will affect portions of the region. Unseasonably warm temperatures, strong westerly winds are forecast. Depending on the how the system tracks across the province, moderate to heavy precipitation is possible in portions of the region. Freezing level 1900m.Saturday: Light precipitation, winds light southwest and freezing level of 1900m.Sunday: Light precipitation, light southeast winds, and freezing level of 1700m.

Avalanche Summary

Slab avalanches to size 1.5 were ski cut and failed naturally in the region. Recent explosives testing in the southern portion of the region producing slab avalanches to size 2.5 isolated to the storm snow.

Snowpack Summary

Light to locally moderate amounts of new snow have fallen adding to an ongoing storm snow instability, particularly on the west side of the region where accumulations have been highest. The new snow is most likely reactive as a wind slab in exposed terrain or as loose snow in sheltered areas. The variably reactive February 12th and 15th surface hoar layers now exist up to 80cm below the surface and seem most prevalent on the west side of the region. This interface may also be reactive on solar aspects where a sun crust exists. A surface hoar layer buried on February 23 is still on the radar of some operators. This layer has been less likely to trigger by skiers, but may still be sensitive to large loads like avalanches in motion or cornice fall. The mid and lower snowpack are generally well settled and strong.

Avalanche Problems

Storm Slabs

Recent new snow and wind have created new slabs, which may be particularly touchy on slopes in the lee of the wind.
Avoid areas with overhead hazard.>Stay well to the windward side of corniced ridges.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5

Persistent Slabs

Loading from new snow and wind may add reactivity to persistent buried surface hoar layers. In deeper snowfall areas, resulting avalanches may be large.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 7