Avalanche Forecast

Issued: Feb 23rd, 2013 10:00AM

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 variable weather conditions

Weather Forecast

Sunday: Light to locally heavy snowfall developing late in the day and continuing overnight / Moderate to strong west winds / Freezing level at 900mMonday: Light snowfall / Light northwest winds / Freezing level at 1100mTuesday: Mix of sun and cloud / Light southwest winds / Freezing level at 1000m

Avalanche Summary

We have had no new avalanche reports from the region.

Snowpack Summary

Light to locally heavy amounts of new snow have fallen. The new snow has been redistributed into deeper wind slabs by locally strong winds, particularly on the west side of the region where accumulations have been highest. These new accumulations are adding load to the weak February 12th and 15th surface hoar layers which now exist up to 80cm below the surface. The slab may also be reactive on southerly aspects where buried sun crusts exist. A surface hoar layer buried on February 23 is still on the radar of some operators. This layer has been less likely to trigger by skiers, but may still be sensitive to large loads like avalanches in motion or cornice fall. The mid and lower snowpack are generally well settled and strong.

Problems

Storm Slabs

The timing and snowfall amounts for a storm forecast for Sunday are uncertain. Where higher accumulations exist, continued storm slab activity will be very likely, especially in wind-affected areas.

Choose conservative lines and watch for clues of instability.>Be cautious as you transition into wind affected terrain.>Make observations and assess conditions continually as you travel.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Persistent Slabs

Loading from new snow and wind will continue to 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, deep avalanches due to the presence of buried surface hoar.>Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Valid until: Feb 24th, 2013 2:00PM