Avalanche Forecast

Issued: Dec 12th, 2014 7:48AM

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 500-1000 m on Saturday and to valley bottom for Sunday and Monday. Winds ease off and become light and variable.

Avalanche Summary

Recent observations are limited from the region but there was a report of a size 2.5 explosive controlled wind slab on Thursday. This slide likely failed on weak layer buried in early December but appeared to step down to the early November crust. On Wednesday, one observer from the McMurdo Hut southwest of Golden reported seeing numerous avalanche crown lines and significant debris, particularly from alpine terrain. Natural activity should taper off this weekend but there may be lingering potential for triggering fresh wind or storm slabs higher in the alpine.

Snowpack Summary

The snow surface likely consists of moist/wet snow or a melt-freeze crust up to 2000-2200 m. Above this elevation there could be up to 40 cm of dense storm snow, which has probably been blasted around by strong southerly winds. In the Golden area a weak layer of surface hoar or facetted snow can be found under the storm snow. The mid pack consists of settled snow, facets, and melt-freeze crusts (primarily lower elevations). The mid-November weak layer (surface hoar, facets, and/or a crust) is buried 60-80 cm deep. Below this you will likely find a thick layer of sugary facets sitting on a solid rain crust from early November. The early November crust/facet layer did become reactive near Golden this week.

Problems

Storm Slabs

An icon showing Storm Slabs
Use caution 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.
Be aware of conditions that change with elevation and use ridges or ribs to avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine.

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.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

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