Avalanche Forecast

Issued: Mar 16th, 2012 10:17AM

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

triley, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

Unsettled conditions are expected for Saturday and Sunday. Light winds and convective snow showers are forecast to bring up to 10 cm on Saturday. Clearing overnight should turn to broken skies during the day on Sunday. There may be some clearing on Monday if a ridge of high pressure extends far enough north. If the ridge does not go far enough north, then expect cloud and scattered flurries to move in from the northwest.

Avalanche Summary

One natural size 2.0 was reported from 1800 metres on a SE aspect that was 50 cm deep on Thursday. Earlier in the week natural avalanches and natural cornice falls up to size 3.5 were reported.

Snowpack Summary

The region has received about 35 cm of new snow in the past 2 days. Recent moderate to strong winds have transported available snow into thick windslabs in the alpine and at treeline, and have added weak new growth to the large cornices in the region. The new snow has added to the well consolidated storm slab that overlies weak surfaces that formed early February. This interface, which lies between 1 and 2 metres below the surface, includes a widespread surface hoar instability that, depending on aspect an elevation, may exist in combination with facets or crusts. These persistent weak layers have been reactive all week and remain a concern at all elevations. The weight of new snow, near-surface avalanches, sleds, and skiers may easily trigger these deeper weaknesses creating unexpectedly large and destructive avalanches.

Problems

Persistent Slabs

Persistent weaknesses are buried upwards of 150cm below the surface. Surprisingly large and destructive avalanches could be triggered naturally by the weight of additional snowfall, or by the energy of a person/sled.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

3 - 7

Wind Slabs

Recent southwest wind and new snow have developed windslabs in the alpine and at treeline. These windslabs may take a few days to settle and bond.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Storm Slabs

The recent storm snow has consolidated into a cohesive slab. Extended sunny breaks may weaken the slab resulting in natural activity. Storm slab avalanches may step down to deeper weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Valid until: Mar 17th, 2012 9:00AM