Avalanche Forecast

Issued: Dec 26th, 2014 8:23AM

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

Avalanche Canada rbuhler, Avalanche Canada

Hazard will increase during the storm on Saturday.  Give the new snow time to stabilize and avoid areas with heavy wind loading.

Summary

Confidence

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

Weather Forecast

A weak storm system reaches the South Coast late Friday or early Saturday morning.15-25mm of precipitation are possible for much of the region on Saturday. Freezing levels should peak at around 1000m and alpine winds are expected to be moderate-to-strong from the NW. A ridge of high pressure builds on Sunday and will persist for several days. Sunday should be mostly clear and dry with freezing levels around 500m and light alpine winds. Monday should be pretty much the same with colder temperatures.

Avalanche Summary

No new observations on Thursday or by publish-time on Friday. On Wednesday, a snowmobiler was involved in an avalanche in the Callaghan area. Details are limited but it sounds like an isolated storm instability was the main problem. On Tuesday, several natural size 1 wind slabs were reported.

Snowpack Summary

The snow surface prior to the storm includes wind scouring or old wind slabs in exposed terrain, and well settled storm snow in sheltered areas.  On top of these surfaces is widespread surface hoar layer up to 10mm in size.  40-60cm below this is the mid-December surface hoar layer. This layer appears to have gained strength and stabilized in most of the region but still may be a concern in the northern parts of the region. Reports suggest that the surface hoar is most prevalent on sheltered north aspect slopes at treeline elevation. Winds prior to burial likely destroyed the surface hoar in the alpine throughout most of the region. The mid and lower snowpack contain several old crust layers but these have generally been unreactive.

Problems

Storm Slabs

An icon showing Storm Slabs
New storm instabilities may form during the storm on Saturday. The main problems are expected to be wind slabs in exposed areas and loose dry from steep features but a more widespread storm slab may form in areas that receive the most snowfall.
Dig down to find and test weak layers before committing to a line.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 27th, 2014 2:00PM