Avalanche Forecast

Issued: Feb 15th, 2012 9:56AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Cornices, Deep Persistent Slabs and Wind Slabs.

triley, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Cloud should move into the region overnight and precipitation is expected to begin by about noon on Thursday. Western parts of the region may get 10 cm combined with moderate to strong southerly winds. The freezing level may rise up to 1300 metres during the day in the west of the region. The eastern parts of the region should see freezing levels rise to about 700 metres and drop back to near valley bottom overnight. Another ridge is forecast for Friday that should bring mostly clear skies and light winds during the day. The next Pacific frontal system is expected to move inland from the coast during the evening. Forecast amounts for the overnight period and during the day on Saturday are light, probably about 10 cm in total.

Avalanche Summary

A natural ice fall resulted in a size 2.5 avalanche

Snowpack Summary

Widespread surface hoar has been buried by a couple of cm of new snow in most of the region. A melt-freeze crust has developed on southerly aspects at all elevations. North and east aspects continue to have dry snow and some surface sloughing in steep terrain. Basal facets have not been reactive, but operators continue to monitor this layer in tests. Triggering this deep persistent weak layer is unlikely, but shallow snowpack areas or shallow weak areas adjacent to deeper wind loaded slopes are suspect locations.

Problems

Cornices

Watch for tender cornices at ridge tops. They may be destructive by themselves, and have potential to trigger large avalanches on the slope below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Deep Persistent Slabs

Although a deep persistent slab would most likely require a large trigger, they are still possible; especially in thin snowpack areas or in unsupported, rocky terrain.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 7

Wind Slabs

Forecast new snow and strong southwest wind are expected to develop windslabs in the alpine and at treeline.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Feb 16th, 2012 9:00AM