Avalanche Forecast

Issued: Mar 26th, 2014 9:50AM

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

mbender, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Thursday: Cloudy with flurries and possible sunny breaks. Freezing level expected at 900m. Ridge winds light gusting to moderate from the west and southwest. Friday: Cloudy with sunny periods and isolated flurries. Light southwest ridge winds. Freezing level rising to 1600m.Saturday: Mainly cloudy with isolated flurries. Accumulations up to 5cm. Alpine temperatures 1 degrees. Freezing level 2000m.

Avalanche Summary

Recent observations are limited to loose snow avalanches on steep unsupported features to size 1.5.

Snowpack Summary

See this great video from our South Rockies field team that does an super job of summarizing the current state of the snowpack.The region has picked up 60 - 100cm of storm snow that fell in the last week. Winds have been out of the SW through NW which has created fresh wind slabs in alpine and treeline lee terrain. These winds have also created large brittle cornices.Around 70 cm of settling storm snow 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 crust 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.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Cornices

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.

Give cornices a wide berth when travelling on or below ridges.>Pay attention to overhead hazards like cornices.>

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 27th, 2014 2:00PM