Avalanche Forecast

Issued: Jan 31st, 2012 9:25AM

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

ccampbell, Avalanche Canada

Cariboos.

Summary

Confidence

Good - -1

Weather Forecast

Wednesday: Another 5-10cm expected with light to moderate southwesterly winds and freezing levels around 1000m. Thursday and Friday: Clear and dry with significant warming by Friday and moderate northwesterly winds becoming light and variable.

Avalanche Summary

Several natural and slope-cut step down slab avalanches Size 2 to 3.5 associated with the mid-January persistent weakness as deep as 150cm occurred on Monday. Check out the incident database (link under the Bulletins tab) for a report of a slope-cut stepping down to the mid-January facets in the Monkton Creek area near Barkerville. The recent storm snow also remains sensitive to human triggers with several Size 1 to 2, 30-40cm thick slab avalanches.

Snowpack Summary

Total snowpack depths are well above average or even new record depths for this time of year. Recent warm temperatures and upside-down storms created a touchy surface slab. Other weaknesses within and under the 150+cm of recent storm snow create the potential for step-down avalanches, but things seem so be settling rapidly. Moderate southerly or southwesterly winds have created wind slabs and large fragile cornices in exposed lee and cross-loaded terrain. Snowpack test results on the mid-January persistent weakness range from no result where it's deeply buried to moderate sudden where it was found as facets overlying a crust down 80cm. This, as well as recent avalanche activity, suggests large persistent slab avalanche that propagate across entire slopes could be triggered, especially by step-down avalanches and cornice falls in shallow snowpack areas.

Problems

Storm Slabs

Large storm slab avalanches have been occurring for the past week and are expected to remain sensitive to triggers for the forecast period.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Wind Slabs

Wind slabs are generally lurking below ridgecrests, behind terrain features and in cross-loaded gullies. They can fail as very large, destructive avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 6

Persistent Slabs

Recent very large avalanche activity suggests persistent weaknesses are once again rearing their ugly heads. Particularly concerning with large triggers such as step-down avalanches and cornice falls.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 7

Cornices

Large cornices are looming over many slopes. A falling chunk could trigger an avalanche on the slope below.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Feb 1st, 2012 3:00AM