Avalanche Canada jlammers, Avalanche Canada

Sea to Sky Avalanche Forecast

Feb 19th, 2012 9:22AM

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

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Monday: Trace amounts of snow / light northwest winds / freezing level @ 1100m Tuesday: Light snowfall during the day increasing to heavy snowfall in the evening / strong to extreme westerly winds / freezing level @ 1100m Wednesday: Light snowfall / strong westerly winds / freezing level@ 800m

Avalanche Summary

Widespread natural, human triggered, and explosive triggered avalanche activity was observed in the Whistler area on Saturday. The avalanches were up to size 2.5 and occurred in response to Friday night's storm. A size 2 skier-triggered slab avalanche occurred on a steep, lee alpine feature in the Spearhead Range on Sunday. My feeling is that isolated human-triggered avalanches up to size 2 will be possible at all elevation bands on Monday.

Snowpack Summary

Heavy snowfall and strong winds on Friday night created new wind and storm slabs and continued to cover an assortment of old snow surfaces that were first buried a little over a week ago. These old surfaces are now about 45cm down and include crusts that exist on all aspects at lower elevations and on steep solar aspects higher up. Facets and spotty surface hoar may also exist in combination with crusts, so there may be continued slab reactivity at lower elevations. The mid and lower snowpack are strong and well settled. The average treeline snowpack depth is about 240cm.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 4
Strong winds and heavy snowfall on Friday night have created wind slabs at treeline and in the alpine.

Aspects:

North, North East, East, South East, South.

Elevations:

Alpine, Treeline.

Storm Slabs

An icon showing Storm Slabs

Likelihood

Possible

Expected Size

1 - 4
Watch for storm slab activity on steep, unsupported terrain. They may be particularly reactive where they exist in combination with buried crusts.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Feb 20th, 2012 9:00AM