Avalanche Forecast

Issued: Dec 12th, 2014 7:38AM

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

Avalanche Canada Peter, Avalanche Canada

Although the trend shows improvement the potential for triggering an avalanche is greatest at higher elevations due to recent heavy snowfall and strong winds.

Summary

Confidence

Good

Weather Forecast

A ridge of high pressure will build over BC resulting in much drier and cooler weather for the next few days. Most areas should see a mix of sun and cloud with slight chance of the odd flurry. Freezing levels should gradually drop to 500 m on Saturday and to valley bottom for Sunday and Monday. Winds ease off and become light and variable.

Avalanche Summary

A widespread natural avalanche cycle with slides up to size 3.5 was reported south of Valemount on Thursday. Large slab avalanches were observed above 2000 m and numerous wet slides were observed at lower elevations in steep terrain. Similar activity was likely in other parts of the region. Natural avalanche activity should taper off heading into the weekend as temperatures cool and conditions dry out; however, it could still be possible to trigger fresh wind slabs or storm slabs at higher elevations where most of the recent precip has been snow.

Snowpack Summary

The snow surface was moist or wet below 2000 m and moist up to around 2400 m. Cooler temperature on Friday may have created a surface crust, possibly with a bit of fresh snow on top. At higher elevations (above 1800 m) there is 30-70 cm of dense storm snow sitting on a sun crust or surface hoar. In exposed alpine areas this new snow has been blasted around by strong southerly winds. Reports from the region suggest that anywhere from 50-150 cm of settling snow overlies one or more weak layers which formed during November. Snowpack tests suggest that these weak layers are getting harder to trigger but still have the potential to produce large avalanches if triggered. Recent wind has likely created deep and dense wind slabs in lee features in exposed alpine terrain.

Problems

Storm Slabs

An icon showing Storm Slabs
This problem is primarily a concern in the alpine where most of the recent precipitation has fallen as snow. Watch for wind loaded or cross loaded slopes well below ridge crests from the past week of strong southerly winds.
Choose well supported terrain without convexities.>Use ridges or ribs to avoid freshly wind loaded features. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
The likelihood of triggering a persistent slab should decrease heading into the weekend but be wary of any slope that did not release during the storms or has been reloaded.
Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

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