Avalanche Forecast

Issued: Feb 22nd, 2013 10:32AM

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

jlammers, Avalanche Canada

Purcells.

Significant snowpack and weather variations exist throughout the region. Be aware of conditions that are specific to your area and make observations continuously as you travel.

Summary

Confidence

Poor - Due to limited field observations on Friday

Weather Forecast

Saturday: Light snowfall / Moderate northwest winds (with strong gusts) / Freezing level at surfaceSunday: Light snowfall / Moderate west winds / Freezing level at 1100mMonday: Light snowfall / Light southwest winds / Freezing level at 1000m

Avalanche Summary

Loose snow avalanches to size 1.5 were reported in a few areas; however, observations have been extremely limited due to poor visibility.

Snowpack Summary

Very light to locally moderate amounts of new snow have fallen and may exist as a wind slab in exposed areas. These new accumulations add to a slab which overlies reactive layers of surface hoar that were buried on February 12th and February 15th. These layers currently sit between 15 and 60cm below the surface. The slab may also be reactive on southerly aspects where buried sun crusts exist. Loading from new snow and wind throughout the weekend may cause another cycle of natural activity, or an increased sensitivity to human triggers in deeper snowpack areas. There are older weak layers that are now buried down around 70-80 cms and also at about 110 cms. These layers have been less likely to trigger by skiers, but they may still be sensitive to large loads like avalanches in motion or cornice fall.

Problems

Storm Slabs

Recent snowfall amounts are highly variable and somewhat uncertain throughout the region due to limited observations. Where higher accumulations exist, large storm slab avalanches are likely, especially in wind-affected areas.

Be cautious as you transition into wind affected terrain.>Make observations as you travel and watch for clues of instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Loading from new snow and wind will likely add reactivity to persistent buried surface hoar layers. In deeper snowfall areas, resulting avalanches may be surprisingly large.

Be aware of the potential for large avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Valid until: Feb 23rd, 2013 2:00PM