Avalanche Forecast

Issued: Feb 25th, 2013 9:12AM

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

Avalanche Canada mbender, Avalanche Canada

Summary

Confidence

Fair - Due to variable snowpack conditions for the entire period

Weather Forecast

Tuesday and Wednesday: Possible sunny breaks with isolated flurries, winds light from the northwest and alpine temperatures -5. Freezing level rising to 800m on Tuesday.Thursday: Light snow, winds light from the southwest and alpine temperatures of -6. Freezing level 900m.

Avalanche Summary

A natural cycle began on Friday and continued on Saturday, with several slabs to size 2.5 failing on all aspects. Many were triggered by wind-loading. They failed within the storm snow or on the mid-Feb surface hoar or crust layers.

Snowpack Summary

In much of the region, up to 65 cm recent snow overlies weak interfaces buried in mid-February (mainly surface hoar/ sun crust layers). The storm slab above these interfaces has the potential for wide propagations and surprisingly large avalanches, especially where winds have shifted the snow into slabs in the lee of terrain breaks. A thin freezing rain/rime crust formed on Friday, which is now buried by about 15 cm snow. Snow forecast overnight Sunday and on Monday will add to these storm slabs.In the Rossland Range, surface hoar which was buried mid-week is 20-30 cm down and exhibits easy, sudden results in snowpack tests. As more snow builds over this layer, it could become touchy.Older snowpack weaknesses buried in the upper snowpack (Feb 4th and Jan 23 surface hoar/facet/sun crust layers) are still being tracked by professionals. There is some potential for triggering one of these deeper layers with a large trigger like an avalanche in motion, or from a thin-spot trigger point. The lower snowpack is generally well settled.

Problems

Storm Slabs

An icon showing Storm Slabs
Loading from new snow and wind has increased the avalanche danger, especially where the wind has shifted snow into slabs behind terrain breaks like ridges and ribs.
Be cautious as you transition into wind affected terrain.>Pay attention to overhead hazards like cornices.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
The presence of weak layers buried in the upper snowpack means there is a risk of triggering surprisingly large slabs.
Avoid convexities or areas with a thin or variable snowpack.>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 - Likely

Expected Size

1 - 6

Valid until: Feb 26th, 2013 2:00PM