Avalanche Forecast

Issued: Mar 31st, 2013 8:15AM

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

Danyelle Magnan, Parks Canada

Glacier.

Danger is increasing to Considerable through the day with solar warming. Danger is lower, and ski quality better, on shaded and sheltered aspects.

Summary

Weather Forecast

The warm and calm weather will continue through the long weekend. Today should be mostly clear. Temps overnight barely hit freezing so it won't take long for crusts to break down. The ridge starts to break down on Monday, with increasing cloud on Tuesday. Alpine temps should start to lower as the next weather system approaches bringing light snow.

Snowpack Summary

Strong solar and warm temps over the past week has resulted in moist surface snow and crusts on all but sheltered N aspects above 1900m. Shallow ridgetops in the alpine are becoming isothermal. On shaded aspects large surface hoar is growing, right to mountain top. A surface hoar/crust layer in the upper meter is becoming isolated and stubborn.

Avalanche Summary

Several glide cracks released yesterday (see photo's), resulting in size 2.5-3 avalanches. Solar triggered avalanches started around 11am, on SE-W aspects. Avalanches are now gouging deeper into the snowpack as it warms up. Below treeline and in shallow areas the snow is becoming weak with warming and can be skier triggered.

Confidence

Problems

Loose Wet

Warm temps overnight didn't allow much of a freeze. The sun will quickly break down crusts, and solar triggered avalanches are expected. Get an early start and avoid terrain traps, especially below treeline, where moist slides could pile up deeply.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Deep Persistent Slabs

Glide cracks, gaping cracks in the snowpack, exist on many slopes and have been failing with the warm temps. They can fail unpredictably, and release the entire snowpack to the ground. Several size 2.5 to 3 glide crack avalanches occurred yesterday.

Avoid slopes with glide cracks.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

Cornices

Cornices are large and unsupported. They are more likely to fail with solar warming, and may trigger deeper slabs.

Cornices become weak with daytime heating, so travel early on exposed slopes.Avoid steep slopes below cornices.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Apr 1st, 2013 8:00AM