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Archived

Avalanche Forecast

Dec 19th, 2011–Dec 20th, 2011
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

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 [email protected].

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.

Avalanche Problems

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

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