Avalanche Forecast

Issued: Feb 24th, 2013 9:49AM

The alpine rating is considerable, 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

Fair - Due to variable snowpack conditions

Weather Forecast

Sunday night and Monday: Light to locally moderate snowfall becoming light on Monday / Strong west winds becoming light northwesterly on Monday / Freezing level at 1100mTuesday: Mix of sun and cloud / Light southwest winds / Freezing level at 1200mWednesday: Very light snowfall / Light southwest winds / Freezing level at 900m

Avalanche Summary

Widespread avalanche activity took place in response to Friday's system. Loose dry and storm slab avalanches to size 2.5 were reported from the region. Continued avalanche activity is anticipated with weather forecast for Sunday night.

Snowpack Summary

On Friday light to locally heavy amounts of snow fell. The new snow was distributed 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 variably reactive 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

Continued snowfall is forecast for Sunday night. Where higher accumulations exist, continued storm slab activity will be very likely, especially in wind-affected areas. In sheltered terrain the new snow may react as a loose dry avalanche.

Be cautious as you transition into wind affected terrain.>Make observations and assess conditions continually as you travel.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Loading from new snow and wind may 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.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Feb 25th, 2013 2:00PM