Avalanche Forecast

Issued: Feb 17th, 2013 9:19AM

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

triley, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Overnight and Monday: A weak ridge of high pressure is expected to give clear skies, light winds, and alpine temperatures dropping down to about -10.0 overnight. The ridge should continue to dominate on Monday bringing mostly clear skies with some valley cloud. The next trough is expected to move across the interior on Monday afternoon or evening bringing high cloud and a chance of light precipitation.Tuesday: Mostly cloudy with a chance of light precipitation and light winds.Wednesday :Another weak ridge is expected to fill in behind the trough, bringing light winds and cloudy skies in the morning. Broken skies and continued clearing in the afternoon.

Avalanche Summary

Skiers continued to release avalanches in the storm snow up to size 2.0 and natural avalanches were reported up to size 3.0 along the highway corridor.

Snowpack Summary

New snow has added to the recent storm slab above the February 12th weak surface hoar layer. This layer is now buried down about 20-50 cms depending on where you are in the region. This variable storm slab is also above a sun crust on Southerly aspects. New wind slabs developed at higher elevations due to the new snow and wind during the storm. These soft new wind slabs may be hiding stiffer wind slabs that are a couple of days older. Deeper persistent weak layers from early February and late January continue to show planar failures when moderate to hard forces are applied to snow profile tests. These deeper layers have not been reactive to the loads associated with recreationalists, but they may be triggered by large loads like an avalanche in motion, or a cornice fall.

Problems

Storm Slabs

New snow has added to the load of the recent storm snow. This storm slab is expected to continue to be reactive above a weak layer of surface hoar and sun crusts.

The new snow will require several days to settle and stabilize.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Wind Slabs

New wind slabs have developed at higher elevations. Older wind slabs may be buried by the new snow and may be difficult to locate.

Avoid freshly wind loaded features.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Persistent Slabs

There are older layers of buried surface hoar and crusts that are unlikely to be triggered by the weight of a skier or sledder, but may be triggered by large additional loads like cornice fall or wind/storm slab avalanches in motion.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Feb 18th, 2013 2:00PM