Avalanche Forecast

Issued: Mar 26th, 2012 10:24AM

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

swerner, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

A series of systems will be crossing the Southern part of the province through the forecast period. Most of the punch will be in the South, leaving the North West with light- moderate precipitation amounts, a dominating SW flow, and above normal temperatures. Tuesday: Snow amounts 2-5 cm. Ridgetop winds moderate from the SE. Freezing levels 1100-1300 m. Wednesday/ Thursday: Moderate snow amounts in the West, lighter accumulations inland. Ridgetop winds strong from the South. Freezing levels near 1000 m, falling to valley bottom Wednesday overnight.

Avalanche Summary

No new avalanche observations have been submitted.

Snowpack Summary

Moderate southerly winds have formed wind slabs in the alpine, and at treeline on lee and cross-loaded terrain. North aspects at higher elevations hold dryer, low density snow in the upper 20 cm. Below this sits a well consolidated, settled mid pack. Crusts have formed on solar aspects at all elevations, becoming moist under sunny skies. Melt-freeze conditions exist below treeline on all aspects. The mid February persistent weak layer, 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, although I feel that triggering may be possible in steep, isolated terrain in some parts of the region. If an avalanche occurs on this weak interface it will be very large and destructive. Below this the snowpack is well settled and strong. Cornices in the area are reported to be very large. Cornice failure could trigger an avalanche on the slope below.

Problems

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 - Likely

Expected Size

1 - 6

Wind Slabs

Variable wind slabs found in the alpine and at treeline. These may exist on lee aspects, and terrain features. Cracking and/or whumphing felt below you is a good indicator of unstable, wind effected snow.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

If the sun is shining, loose wet avalanches are likely on solar aspects. Snowballing, pinwheels, and moist surface snow all all indicators of snowpack deterioration. Best to avoid slopes with these conditions.

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

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