Avalanche Forecast

Issued: Mar 27th, 2014 9:13AM

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

mbender, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Friday: Cloudy with sunny periods and isolated flurries. Light southwest ridge winds. Freezing level rising to 1600m.Saturday: Mainly cloudy with isolated flurries and some sunny breaks. Alpine temperatures 1 degrees. Freezing level 1600m.Sunday: Cloudy with flurries. Light southerly winds. Freezing level 1700m

Avalanche Summary

Recent observations are limited to loose snow solar induced avalanches running in steep terrain.

Snowpack Summary

See this great video from our South Rockies field team that does an awesome job of summarizing the current state of the snowpack.Recent winds have been primarily out of the southwest, which has created fresh wind slabs in alpine and treeline lee terrain. Cornices have also become large and unstable. 60-90 cm of settling storm snow from the past week rests on a graupel layer that can be found in much of the region. This makes for around 90 cm on top of the mid march crust at this point. This crust exists on all aspects below 2000m and on solar aspects in the high alpine. North of Sparwood and in the Crowsnest Pass area, the buried crust seems more specific to previously sun-exposed slopes. The deep facet/crust persistent weakness buried at the beginning of February (now down up to 150cm) seems unlikely to trigger in areas where the hard, supportive exists. No matter where you are in the region, this weakness should stay on your radar as any activity at this interface would be large and destructive. Possible triggers include a large cornice fall, a large input in a thin snowpack area or solar warming.

Problems

Wind Slabs

Moderate southwest winds have created wind slabs in the lee of terrain features. Cornices in the region are now very large and fragile. A cornice fall could be destructive by itself or could act as a trigger for a deeply buried persistent weak layer.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

The deep weak layers that formed in early February may be a bit touchier in the north of the region. Possible triggers at this point include a large cornice fall, surface avalanche in motion or solar warming.

Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 28th, 2014 2:00PM