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Avalanche Forecast

Dec 18th, 2012–Dec 19th, 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
4: High
The avalanche danger rating in the alpine will be high
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
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 Rockies.

Confidence

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

Weather Forecast

Overnight and Wednesday: A weak ridge of High pressure will continue to cause cold and dry conditions during the day. The next Pacific frontal system is expected to move into the region by Wednesday evening. Light Westerly winds will become moderate Southwesterly as the storm moves in and brings 10-15 mm of precipitation, that should be snow (15-20 cms) at all elevations.Thursday: Strong Southwest winds and another 10-15 mm of precipitation for southern areas of the region. Freezing level should remain at valley bottoms.Friday: Flurries and gusty Northwest winds as a cold arctic airmass moves in from the Yukon.

Avalanche Summary

No observations were made due to poor visibility. One loud avalanche was heard running in the alpine during the afternoon.

Snowpack Summary

During the storm on Monday the height of the snowpack in Harvey Pass was 225 cms at 2000 metres. There was 20 cms of new snow and the storm slab was 45 cms thick. Moderate to strong Southwest winds were moving snow at treeline all afternoon. There was about another 15 -20 cms of snow after these observations. There was cracking in the soft slab ahead of skis when travelling. We suspect that stiffer wind slab was forming at higher elevations.

Avalanche Problems

Storm Slabs

The new storm is expected to develop a storm slab on all aspects. The forecast strong SW winds may transport storm snow into thick and touchy slabs on North thru East aspects.
The new snow will require several days to settle and stabilize.>Be cautious of sluffing in steep terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5