Avalanche Forecast

Issued: Jan 27th, 2015 8:13AM

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

Avalanche Canada esharp, Avalanche Canada

Avalanche danger will drop as the temperature cools, however, a widespread melt-freeze crust will make for challenging riding.

Summary

Confidence

Fair

Weather Forecast

Freezing levels will continue to drop as a cold front moves across the province.  A ridge of high pressure will build over the coast Wednesday resulting in clear skies and light SW winds over the interior.  A weak front will move across the province on Friday and may produce isolated flurries.

Avalanche Summary

As the temperature drops I expect that avalanche activity will slow down.   The recent snow, rain, and wind were a great test of buried persistent weaknesses in the snowpack and resulted in a widespread avalanche cycle.  The mid-January surface hoar layer has been responsible for the majority of the recent avalanche activity although there have been reports of occasional releases to ground or the mid December layer in the Selkirks.

Snowpack Summary

I suspect that freezing levels rose to about 2800m during the recent warm spell and that rain saturated the upper snowpack.  At upper elevations the surface is heavily wind affected.  A breakable crust already exists in the alpine and as the freezing level continue to drop down to the valley floor a widespread melt freeze crust will form on all aspects and elevations.  I suspect that at lower elevations warm moist snow may have destroyed the mid-January surface hoar layer.  Where it still exists it can be found down between 40 and 80 cm.  The midpack is broken by the mid-December surface hoar layer that is now 80 to 140cm below the surface.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A layer of weak surface hoar siting on a crust is buried by 40 to 70 of moist snow has been responsible for most of the recent avalanche activity.
Avoid convexities or areas with a thin or variable snowpack.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
A deeper layer of surface hoar is still producing the occasional large avalanche given a large enough trigger in the right spot. It is especially a concern on open slopes around treeline. 
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Do not travel on slopes that are exposed to cornices overhead.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Jan 28th, 2015 2:00PM