Avalanche Forecast

Issued: Dec 29th, 2011 9:53AM

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

ghelgeson, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Another significant storm enters the region Thursday evening continuing into Friday. Moderate to heavy precipitation is expected with total accumulations around 20 cm. Alpine winds will be blasting out of the SW from 55 - 80 km/h. Temperatures are expected to be mild with a daytime high of 0 and an overnight low of -3. This looks to be the last storm associated with the recent active weather pattern. Heading into the weekend a strong ridge builds over the interior bringing dry conditions.

Avalanche Summary

Limited visibility yesterday 111229 = No recent observations. Suspect continued natural avalanche activity.

Snowpack Summary

50-100 cm of total storm snow has been reported. Rising temperatures during the storm are likely to have helped form slabs within the new snow. Wind slabs exist on slopes lee to the west in the alpine and in open areas at treeline and below. A surface hoar/facet/crust interface is buried anywhere from 80-100cm deep. Avalanche activity on this layer has slowed, but it remains a concern as snow-loading gradually builds this week, particularly on slopes which did not avalanche last week. This layer is still showing easy results in some areas. A low elevation melt-freeze crust buried about half a meter deep is also one to watch. A sun crust is also buried in the alpine on some steep south and west aspects. The mid-pack is generally strong and well settled.

Problems

Storm Slabs

The region has seen 100 cm since Christmas with another 20 cm on tap for Friday. An avalanche originating in the storm snow could step down and trigger a persistent slab avalanche.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Wind Slabs

Big winds combined with plenty of snow available for transportation have resulted in widespread wind slabs. Watch for signs of wind loading; fat pillow like formations & blowing snow.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Persistent Slabs

A surface hoar layer buried approximately a meter below the snow surface is capable of producing large & likely un-survivable avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Valid until: Dec 30th, 2011 8:00AM