Avalanche Forecast

Issued: Mar 26th, 2012 10:28AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

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, but the Cariboo's will see light- moderate precipitation amounts, and a dominating SW flow with above normal temperatures. Tuesday: Snow amounts 2-5 cm. Ridgetop winds light from the South. Treeline temps near 2 degrees. Freezing levels 1700 m. Wednesday: Snow amounts 5-10 cm. Ridgetop winds moderate from the SW. Freezing levels 1200-1400 m overnight, rising to 1600 m during the afternoons. Thursday: Light-moderate snow amounts. Ridgetop winds mod-strong from the SW. Freezing levels 900 m.

Avalanche Summary

On Monday a size 2.5 natural cornice fall triggered the slope below. This was at 2400 m, on a North aspect. On Sunday, a size 3 natural, solar induced slab avalanche was reported from the Miledge Creek area. This ran in steep, unsupported terrain. No other observations reported. On Saturday three, size 3 natural avalanches were observed in steep, rocky, unsupported terrain. They occurred between 2000-2800m on north to east aspects and are suspected to have run on the February persistent weak layer.

Snowpack Summary

Recently formed wind slabs exist in the alpine and at treeline. Solar radiation has led to moist surfaces on sun exposed slopes with good crust recovery developing at night. Cornices have grown large and have become unstable; they may act as a large trigger on slopes below. A consolidated slab overlies a persistent weak layer that was buried in early February. Now 1-2 m below the surface, these weaknesses include surface hoar, facets or crusts. Concern still exists about the potential for deep and destructive releases at this interface. This may be a low probability, high consequence problem.

Problems

Cornices

An icon showing Cornices
Large cornices exist and are becoming more likely to fail, especially when temperatures fluctuate. A cornice fall could trigger a very large avalanche on the slope below.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
A weak interface down 1-2 m remains concerning. While avalanches on this layer have become less frequent, those that do release are very large and destructive.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 8

Wind Slabs

An icon showing Wind Slabs
Variable wind slabs found in the alpine and at treeline. These 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

Possible - Likely

Expected Size

1 - 4

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