Avalanche Forecast

Issued: Mar 5th, 2012 9:31AM

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

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Good

Weather Forecast

Flurries are expected to end today and skies should clear by dinner time causing overnight temperatures to drop below freezing in the valley bottoms. Tuesday is forecast to be sunny with light northwest winds at ridgetops. Alpine temperatures should stay close to -10.0 in the afternoon. Steep solar aspects may see some moist snow at treeline. High pressure is expected to continue to dominate the area on Wednesday causing continued clear skies and light northerly winds. Clear skies are forecast to continue on Thursday morning. The wind is expected to veer to the southwest by the afternoon, and the freezing level may rise up to about 2200 metres in advance of the next system moving in from the Pacific.

Avalanche Summary

A couple of small size 1.0-1.5 thin slab avalanches were reported from Sunday. Some of the large rock slab features along the Coquihalla highway corridor were starting to slide; these are not in terrain suitable for recreation. I suspect that there will be reports of more activity as the storm clears and operators can see some alpine terrain.

Snowpack Summary

There has been about 50 cm in the past 24 hours in the Coquihalla area, and about 35cm in the Duffey Lake area. Moderate to strong southerly winds created windslabs in the alpine and at treeline. The freezing level went up to about 1600 metres on Sunday causing moist snow up to about 1800 metres. A trailing cold front brought the temperatures down at the same time as the most intense snowfall. A weak layer of buried stellar crystals and/or decomposed and fragmented crystals is now buried by about 70-90 cm of storm snow. The new windslabs may take a couple of days to settle and bond.

Problems

Wind Slabs

An icon showing Wind Slabs
Windslabs may take a couple of days to settle and bond.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Storm Slabs

An icon showing Storm Slabs
New snow at higher elevations and freezing levels up to about 1500 metres have developed a reactive storm slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Persistent Slabs

An icon showing Persistent Slabs
New snow will add to the load above the persistent weak layers of preserved stellars, facets, buried surface hoar and crusts. Avalanches sliding on this layer may be large and destructive.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Mar 6th, 2012 8:00AM