Avalanche Forecast

Issued: Apr 19th, 2013 8:07AM

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.

New snow overnight has elevated the avalanche danger. Spring conditions exist and hazards like breakable crust, cornice fall and glide crack failures should not be overlooked.

Summary

Weather Forecast

Moderate precipitation is forecast to continue today. Freezing levels will rise to around 1800 m with moderate SW winds. Light snow will continue tonight and Saturday with freezing levels dropping slightly to 1400 m. The forecast is a drying out on Sunday as a warmer air mass moves in and again rises freezing levels to around 1800 m.

Snowpack Summary

Up to 10 cm of new snow has fallen overnight 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, some terrain 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.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.

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.

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 20th, 2013 8:00AM