Avalanche Forecast
Issued: Dec 29th, 2011 10:41AM
The alpine rating is Wind Slabs, Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertainfor the entire period
Weather Forecast
Friday: Light snowfall, perhaps 10-15cm accumulation. Moderate westerlies.Saturday: Light snow. Freezing level near surface. Moderate westerlies. Sunday: Moderate precipitation. Freezing level rising to 1400m in the afternoon.
Avalanche Summary
Highways avalanche control produced numerous Size 2-3.5 slab avalanches. The largest of these failed at ground, up to 4m deep.
Snowpack Summary
Over the past week the northwest has been slammed by snow, strong to extreme winds, and fluctuating freezing levels. The week's tally is closing in on 200cm near Terrace, with areas to the north seeing a little less (Stewart up to 120cm). New snow has been blown around by strong south to southwest winds creating wind slabs on lee slopes and scoured windward slopes.In addition to the more obvious direct-action storm instabilities, local avalanche professionals have some other concerns: Surface hoar that formed during the winter solstice sits approximately 50-70cm below the surface. As well, the crust-facet combo (extends up to alpine elevations in the south and to 1000m in the north) from the early December dry-spell sits about 160cm below the surface and has not gone away. Any avalanches on this layer would be highly destructive and are probably waiting for the right load or trigger. Add the new observations of avalanches failing at ground and we have quite a package.
Problems
Wind Slabs
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 30th, 2011 8:00AM