Avalanche Forecast

Issued: Apr 20th, 2013 8:00AM

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

catherine brown, Parks Canada

Glacier.

Conditions vary greatly with elevation. Expect many different surface conditions and keep an eye out for springtime hazards like cornice fall and glide cracks.

Summary

Weather Forecast

Light snow will continue today and tonight. Freezing levels are forecast to be around 1400 m with moderate NW winds. The skies will clear for Sunday and Monday as an upper ridge builds.

Snowpack Summary

Up to 20 cm of new, heavy snow has fallen in the last couple days at treeline and above. This covers a variety of surfaces including sun crust, small surface hoar and moist isothermal snow. The April 3rd crust is down around 50-60 cm. Below treeline snow is isothermal, on some terrain snow still has some hardness and strength to it.

Avalanche Summary

On Monday, there was a skier accidental, size 3.0 on the east face of Mt Swanzy, depth 100cm, 150m wide, suspect April 3 crust. Skiers were not involved, and later the same day a skier accidental, size 2.0, Forever Young couloir, ran to 2/3 fan. Skier got taken down to the fan before self arresting. Both were in the extreme alpine terrain.

Confidence

Due to the number of field observations

Problems

Storm Slabs

New snow snow could be skier triggered. Natural avalanches triggered by continued snowfall and wind loading are possible today. Watch for clues of instability. These could include recent avalanche activity and settlements or cracking while skiing.

If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.Make observations and assess conditions continually as you travel.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

Firm, wind deposited snow is now buried by new snow at treeline and in the alpine. Use your ski pole to feel for these layers. Reverse loading by N-NE winds has loaded S-SW exposed terrain as well. S-SW winds overnight will be creating fresh slabs.

Avoid lee and cross-loaded terrain near ridge crests.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Persistent Slabs

Large avalanches are still being human triggered as was demonstrated Monday occurring on deeper weak layers. Small surface avalanches may trigger these deeper persistent slabs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Apr 21st, 2013 8:00AM