Avalanche Forecast

Issued: Feb 17th, 2013 9:16AM

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

triley, Avalanche Canada

Purcells.

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

A natural avalanche cycle was reported to have occurred during the storm.

Snowpack Summary

The latest storm did not make it into most of the region. The February 12th weak layer of surface hoar is buried down anywhere from 15 cms in the Northeast of the region to 60 cms in the Southwest of the region. The January 23rd layer is buried down about 100 cms and continues to be a concern for professionals. Cornices are reported to be large and weak, and may fall off naturally.

Problems

Storm Slabs

The buried February 12th surface hoar layer is expected to continue to be reactive. The amount of snow above the weak layer is variable across the region.

The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Wind Slabs

New wind slabs have developed at higher elevations in areas that received new snow and wind.

Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

There are a couple of older layers of buried surface hoar and crust combinations that are buried down about 70 cms and 100 cms, that may be triggered by large additional loads.

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

Possible

Expected Size

2 - 5

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