Avalanche Forecast

Issued: Mar 8th, 2013 9:35AM

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

slemieux, Avalanche Canada

Purcells.

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain on Sunday

Weather Forecast

Friday night and Saturday: The dominating feature is a ridge of high pressure over the whole province bringing warmer air (-4 in the alpine), freezing levels rising to 1600 m., clear skies and light NW winds. Sunday: The ridge is breaking down in the North and remains in the Southern part of the interior range. There is a chance of light precipitation for Sunday (5-10 mm) with winds picking up in the moderate range from the W. Temperatures are slightly cooler than Saturday.Monday: Another system which could deliver more precipitation is expected for Monday but the timing and intensity is still uncertain.

Avalanche Summary

Several natural and skier triggered loose dry avalanches size 1 were reported which ran in the new snow in steep rocky terrain.

Snowpack Summary

The solar radiation and temperatures increasing tomorrow (especially in the Southern part of the region) will weaken the surface of the snowpack especially on S facing slopes. This could possibly trigger the recent wind slabs in the alpine lee areas and below lee ridgetop at treeline. Large looming cornices exist on ridgelines and could also be triggered by the warmth and sun creating a significant load on the slopes below. Buried beneath (60-90 cm) exists a surface hoar and a sun crust layer, which continue to be lingering concerns. A cornice fall could trigger this deeper instability potentially creating large avalanches.

Problems

Wind Slabs

The soft slabs located below ridge tops and in open areas could become weaker especially on S facing slopes.

Watch for wet loose or slab activity with forecast solar radiation and warm temperatures.>Travel one person at a time on all slopes capable of producing an avalanche.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Persistent Slabs

Persistent weak layers exist buried down 60-90 cm, comprising of surface hoar and a sun crust. A cornice fall could definitely trigger this layer..

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Do not travel on slopes that are exposed to cornices overhead.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 6

Loose Wet

Forecasted solar radiation and warmer temperatures will weaken the surface of the snow creating loose moist/wet avalanches.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 9th, 2013 2:00PM