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Avalanche Forecast

Mar 15th, 2015–Mar 16th, 2015
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
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
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
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: South Rockies.

Forecast heavy snow and wind will result in high avalanche danger.

Confidence

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

Weather Forecast

Snow above 1000 metres combined with moderate southwest winds tonight and Monday morning. 15-30 cm of snow is forecast for alpine elevations by late Monday morning. Monday should be cloudy with some lingering flurries and light easterly winds. Freezing levels should drop down to valley bottoms by Tuesday morning. Mostly sunny with light winds on Tuesday and freezing levels rising up to about 2000 metres. Cloudy on Wednesday with moderate southwest winds and light precipitation.

Avalanche Summary

No new avalanches reported. I expect that forecast new snow and wind will develop new storm slabs in the alpine and at treeline on all aspects.

Snowpack Summary

Up to 40 mm of rain fell on Saturday that may have been snow above 2000 metres. Gradual cooling and forecast heavy precipitation for Sunday night and Monday are expected to develop new storm slabs above various old surfaces including moist or wet snow, crusts, old windslabs, and possibly surface facets on high alpine north aspects. There is not enough snow at below treeline elevations for avalanches at this time. If the freezing levels drop to valley bottom we may see new snow covering some areas that have been bare ground. The most prominent snowpack feature is a thick crust 10-30cm below the surface (before the ongoing storm), extending up to around 2200m elevation. The support of this crust is breaking down in response to warm temperatures. Persistent weak layers below this crust still react in snowpack tests and could wake up with continued warming or loading.

Avalanche Problems

Storm Slabs

Forecast heavy precipitation combined with wind is expected to result in new storm slabs on all aspects in the alpine and at treeline.
Avoid avalanche terrain during periods of heavy loading from new snow and wind.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Deep Persistent Slabs

Recent very warm temperatures followed by heavy rain, and then the forecast snow and wind, may be too much change for the snowpack to manage. Avalanches releasing on the deeply buried weak layers are expected to be large and destructive.
Be aware of thin areas that may propogate to deeper instabilites.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6