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Archived

Avalanche Forecast

Dec 16th, 2012–Dec 17th, 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
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
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
2: Moderate
The avalanche danger rating in the alpine will be moderate
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

Regions: Purcells.

Confidence

Fair - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

Overnight and Monday: A Low pressure system moving along the U.S. border will push some precipitation up into the region. Expect 5-10 mm of precipitation falling as snow at all elevations by Monday morning. Strong SW winds during the storm should become strong NW winds after it passes to the East. Alpine Temperatures should be -7.0 during the day.Tuesday: Dry and cool with Alpine temperatures down to about -13.0 combined with strong NW winds.Wednesday:Continued dry and cool, temperatures dropping down to -16.0 in the Alpine. The next Pacific system is forecast to move in from the coast during the evening.

Avalanche Summary

No new avalanches have been reported.

Snowpack Summary

Thin windslabs have developed in the alpine and at treeline in exposed terrain. Some loose snow sluffing may be experienced in steep terrain. Snow pit test results continue to show weak layers of surface hoar that were buried during mid and late November, however we have not seen any activity on these layers recently. The early season rain crust is another layer that continues to show results in tests, but has not been active. Forecast new snow and strong SW winds are expected to continue to develop wind slabs in the alpine and at treeline.

Avalanche Problems

Wind Slabs

Wind slabs are expected to continue to develop due to forecast new snow and strong Southwest winds.
Avoid freshly wind loaded features.>Travel on ridgetops to avoid wind slabs on slopes below.>The new snow will require several days to settle and stabilize.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 5

Persistent Slabs

Buried surface hoar layers continue to give results in snow pit tests. This layer may be triggered from thin weak spots on or adjacent to unsupported terrain features.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5