Avalanche Forecast

Issued: Mar 26th, 2012 10:53AM

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

mpeter, Avalanche Canada

Kootenay Boundary.

If the freezing level does not recover overnight, expect the Below Treeline Danger to be Considerable.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Tuesday: Expect an unsettled day, with flurries and moderate southerly winds. Accumulations could reach 10cm and freezing levels could rise to 1600m. Wednesday / Thursday: A series of fast moving systems will bring short duration snowshowers under continued moderate south-southwesterly winds. Freezing levels could climb to 1600m each afternoon. 15cm are possible each day.

Avalanche Summary

We have reports of loose, moist avalanches being triggered by solar radiation on sunny slopes on the weekend. A fatal avalanche incident occurred in this region on Wednesday. We will post more details when they become available.

Snowpack Summary

The recent warm, clear weather has left us with an aggressive melt freeze crust on solar aspects well into the alpine while shady, dead north slopes have grown some small surface hoar and remain powdery. In some areas up to 15cm of new snow now overlies these surfaces. New windslabs are forming at ridgecrest under the increased winds. Large cornices loom in the alpine. In recent snowpack tests, the early February surface hoar remains well preserved down 100-180cm and continues to yield sudden results. Although unlikely, triggering this layer would yield a very large, destructive avalanche.

Problems

Cornices

Cornices are very large and will grow under the current conditions. There is potential for triggering deep slabs on underlying slopes.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 6

Wind Slabs

The increased wind and new snow are beginning to form new windslabs in lee locations at ridgecrest.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

The deep nature of the mid-February surface hoar layer makes potential avalanches triggered on this layer large and destructive. Avoid thin snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 8

Valid until: Mar 27th, 2012 9:00AM