Avalanche Forecast

Issued: Jan 12th, 2014 8:18AM

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

Avalanche Canada bcorrigan, Avalanche Canada

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Overnight: 10 to 20 cm precipitation forecast, winds strong from the W, freezing levels near 900m.Monday: 10 to 20 cm, winds strong from the W,  freezing levels rise to 1200m.Tuesday: Light flurries, moderate to strong winds from the west, freezing levels may rise to 1400m in parts of the forecast area.Wednesday: No precipitation in the forecast, freezing levels continue to rise as high at 1900m in some parts of the forecast area.

Avalanche Summary

There have been reports of easily triggered soft slabs and large surface sluffs in moderately steep terrain, with the slab avalanches  propagating quite far. A natural avalanche cycle has been reported throughout the forecast area with avalanches up to size 3. Buried persistent weaknesses may now become reactive with heavy loading from snow and wind.

Snowpack Summary

Some parts of the forecast area have received over 50cm of storm snow, which now overlies a variety of old surfaces ranging from wind slabs, to a soft layer of facetted snow and/or surface hoar from earlier in January now buried in the snowpack between 40 and 60 cm.100cm or more below the surface there is a thin melt freeze crust below 2100m elevation, as well as other buried weak layers (surface hoar, facetted snow, and/or a crust) that continue to be reactive in snowpack tests. There are two deeper layers of note. The late-November persistent weak layer is a sun crust on steep south facing slopes and surface hoar in sheltered areas and now may be180 to 200cm below the surface. The October deep persistent weak layer consists of a layer of facets sitting on a crust at the base of the snowpack. This layer is predominantly found on northerly aspects at tree line and in the alpine. The depth of both these layers makes directly triggering an avalanche on them unlikely (maybe a heavy load on a thin spot in steep terrain),  an avalanche stepping down to this layer might dramatically increase the size of the avalanche.

Problems

Storm Slabs

An icon showing Storm Slabs
The possibility of large and destructive avalanche is now with us. Careful route selection is needed to avoid triggering large avalanches.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>The new snow will require several days to settle and stabilize.>Avoid all avalanche terrain.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 13th, 2014 2:00PM

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