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Avalanche Forecast

Feb 27th, 2012–Feb 28th, 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
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

Check out the forecasters blog on managing the current hazard:http://bit.ly/sF10fT

Confidence

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

Weather Forecast

Tue: Clear skies. Alpine Winds Mod, increasing to Strong in the afternoon, W/SW. 1500m Temp: H: -2, L: -11Wed: A low pressure system tracks S of the int'l border, but should deliver 5 -10 cm's to the So. Rockies throughout the day. Alpine winds Strong West. 1500m Temp: H: -0, L: -15

Avalanche Summary

No avalanche activity reported, but, I suspect there was a fair amount of activity Monday as the snowpack adjusted to it's new load.

Snowpack Summary

Saturday night into Sunday, moisture in the west of the region collided with cold air in the east and resulted in an intense period of heavy snowfall that was very low density. This new snow has likely settled a bit with daytime warming Monday. Now 50-60 cm of recent snow sits on a highly reactive weak layer of crusts, surface hoar and facets. At 1950 metres elevation we have some snow pack test results from Friday that show that the 40 cm slab of snow above the February 8th weak layer is sliding with easy to moderate forces applied and it is propagating widely with either sudden planar or sudden collapse characteristics. The slab is reported to be less consolidated on northerly aspects than it is on southerly aspects. In areas further north, less snow has fallen on this interface--in the northern Elk Valley for instance, only around 15-20 cm lies above this interface. In lower snow areas, avalanche activity will likely lag behind higher snow areas, except for areas which have seen significant wind transport. In general, the mid-pack is quite strong in most locations. However, lingering concern remains for basal facets, particularly in shallower snowpack areas with steep, rocky start zones.

Avalanche Problems

Loose Dry

Light dry snow that fell over the past few days has been sloughing in steep terrain and running far and fast.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Previous windslabs are getting buried by dry light snow. New windslabs may develop from forecast west/southwest winds.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 5

Persistent Slabs

The weak layer of buried surface hoar, facets, and crusts continues to be triggered by light additional loads. Avalanches are expected to get larger as the slab above settles and consolidates. This weak layer may propagate into low angle terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 6