Avalanche Forecast

Issued: Jan 8th, 2015 7:32AM

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.

Avalanche Canada Peter, Avalanche Canada

It's important to make conservative terrain choices even though the avalanche danger is slowly decreasing. The consequences of triggering a persistent slab remain high.

Summary

Confidence

Fair - The weather pattern is stable

Weather Forecast

Synopsis: A strong ridge of high pressure should maintain dry conditions with possible valley cloud for at least the next few days. A slight temperature inversion should stick around through Saturday with mountaintop temperatures getting close to 0 degrees. A weak upper trough slides across the province on the weekend, but this might only result in a bit more mid-level cloud and a chance of flurries. By Sunday the inversion should disappear. Winds are light gusting to moderate from the W-NW throughout the period.

Avalanche Summary

Most areas reported a fairly widespread and large natural avalanche cycle on Tuesday. Many of these slides stepped down to mid-December persistent weak layer and produced avalanches up to Size 3.5. There were also reports of skiers and machines triggering slab avalanches from a distance (remotely and sympathetically triggered). Most reported avalanches occurred above 1900-2000 m from a variety of aspects.

Snowpack Summary

Warm temperatures and previous rain have probably created a surface crust on steep solar aspects and all slopes below around 1800 m. Dry powder can still be found at higher elevations. Around 30-60 cm of settling storm snow overlies a variety of old surfaces which include heavily wind-affected surfaces in exposed locations, faceted powder and buried surface hoar in sheltered terrain. Buried 80-100 cm deep, you'll likely find a touchy weak layer of surface hoar sitting on a thick rain crust. This widespread persistent weakness exists at all elevation bands, and continues to be the primary layer of concern for the region. With the recent load of storm snow, I expect this layer to remain active with the potential for large and destructive avalanches. At the base of the snowpack, a crust/facet combo appears to have gone dormant for the time being.

Problems

Storm Slabs

An icon showing Storm Slabs
Forecast sunshine and mild temperatures could maintain touchy storm slab conditions and trigger loose wet slides on steep sun-exposed slopes.
Choose well supported terrain without convexities.>Use careful route-finding and stick to moderate slope angles with low consequences>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Persistent Slabs

An icon showing Persistent Slabs
There is potential to trigger avalanches on a weak layer buried 80-100 cm deep. Be vary wary of slopes that did not slide slide during the last storm and be aware of the potential for triggering slabs from a distance.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Jan 9th, 2015 2:00PM