Avalanche Forecast

Issued: Feb 15th, 2012 9:36AM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Cornices and Wind Slabs.

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Cloud should move into the region overnight and precipitation is expected to begin by about noon on Thursday. Western parts of the region may get 10 cm combined with moderate to strong southerly winds. The freezing level may rise up to 1300 metres during the day in the west of the region. The eastern parts of the region should see freezing levels rise to about 700 metres and drop back to near valley bottom overnight. Another ridge is forecast for Friday that should bring mostly clear skies and light winds during the day. The next Pacific frontal system is expected to move inland from the coast during the evening. Forecast amounts for the overnight period and during the day on Saturday are light, probably about 10 cm in total.

Avalanche Summary

Some sloughing in steep terrain up to size 1.0 that are running fast in the combination of light new snow, large surface hoar, and near surface facets. A few areas have reported pockets of soft slab that are reactive at treeline up to size 1.0

Snowpack Summary

A couple of cm fell in the south of the region on Monday night. This brings the total amount of new snow to about 10 cm above the February 08 surface hoar and near surface facets. Some areas are reporting that thin new windslabs have developed in the alpine due to a period of moderate northerly winds on Monday. The surface hoar layer is at all elevations and aspects, and continues to grow due to clear cold nights. Some areas have reported a very light freezing drizzle that had mixed with some rimed stellars to form a thin soft crust above the recently buried surface hoar layer(120208 SH). Warm alpine temperatures and solar radiation have developed a melt-freeze crust on southerly aspects in the alpine and on all aspects below about 1300 metres. There is some concern regarding facetting below the crust due to recent cold nights. There are a couple of layers that are buried between 25-35 cm that give resistant planar results from tests when hard forces are applied. The mid pack is generally well settled and well bonded. Deeper weaknesses in the snowpack are less of a concern; however, in the southern end of the region there is still talk of basal facets as some operators are avoiding thin and rocky alpine features. This represents a very low probability-high consequence scenario. Large cornices are also widespread in the alpine.

Problems

Cornices

An icon showing Cornices
Cornices may weaken and fall off naturally due to the effects of day time warming and overnight cooling.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Wind Slabs

An icon showing Wind Slabs
Forecast strong southwest winds and new snow are expected to form new windslabs. Various thin windslabs exist due to recent northerly winds, and down flowing wind on glaciated features.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Feb 16th, 2012 9:00AM