Avalanche Forecast

Issued: Dec 19th, 2011 9:44AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Thursday

Weather Forecast

Moderate snow amounts expected through Tuesday easing off in the afternoon. Strong southwest ridgetop winds switching from the northwest later in the day. Freezing levels may rise to 1000m then falling to valley bottom overnight. Wednesday brings mainly dry conditions with few flurries and winds from the southwest. Thursday and Friday light-moderate amounts of snow expected.

Avalanche Summary

On saturday evidence of a size 2 natural avalanche cycle was reported in the Hankin area. There was also human triggering to size 2.5 in the same area. It is thought that these slides are releasing on the crust/surface hoar/facet interface. Forecast weather is uncertain for monday. If precip values are on the high side, expect another spike in natural avalanche activity for the region.Any information (professional or recreational) from the field is highly appreciated. Please send your observations to forecaster@avalanche.ca.

Snowpack Summary

Monday the region has received snow amounts from 5cm-15ms. It continues to snow into Tuesday accompanied by strong southwest winds. Storm snow and wind slabs are forming. There could be up to 50cms total from last week's snowfall and the current snowfall loading the weak layers in the upper part of the snowpack. These weak layers are the December 12th surface hoar/crust/facet combo. Observations made suggest there is facetting above and below the crust. The crust being a result from rain in the early December dry spell. This crust is widespread and is lingering in most start zones up to 2000m. In short, the upper snowpack is variable and showing easy shears in test results. The midpack seems to be well settled and strong.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs have developed on lee and cross-loaded terrain in the alpine and at treeline. Rider triggered wind slabs are likely.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
Reactive storm slabs have now formed at all elevations. Especially where the early December buried surface hoar/crust/facet layers exist.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Dec 20th, 2011 8:00AM

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