Avalanche Forecast

Issued: Mar 20th, 2012 4:00PM

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

pmarshall, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Wednesday: Light convective snowfall - 5-10cm. The freezing level rises to 400-500m during the day. Winds are moderate from the SW. Thursday: Isolated flurries with possible sunny breaks in the afternoon. Freezing level rising to 600m. Winds are light from the SE. Friday: A mix of sun and cloud. Freezing level rising to 600-800m during the day.

Avalanche Summary

No new slab avalanches have been reported in the past day or two. There were a few reports of cornice failures, but most did not trigger slabs.

Snowpack Summary

A dusting of new snow covers the previous surface which included a sun crust on southerly aspects, surface facets or surface hoar in cool shady areas, and pockets of wind slab in exposed terrain. The mid February persistent weak layer interface, comprised of spotty surface hoar, facets and crusts, is buried 80-120 cm below the surface. No recent activity has been reported on this interface. However, recent snowpack tests have been giving hard but sudden "pop" results and indicate it is has the potential to react given the right trigger in the right place. For route selection, it should still be on your radar and is more likely to be triggered on steeper, unsupported terrain. Cornices in the area are reported to be very large and primed for natural collapse or triggering by a person.

Problems

Wind Slabs

New wind slabs may form in exposed lee and cross-loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Large cornices exist in alpine terrain. A failure could be destructive by itself, and could also trigger an avalanche on the slope below.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 6

Persistent Slabs

The likelihood of triggering persistent layers buried in early February is greatest on steep, unsupported terrain .

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 21st, 2012 9:00AM