Avalanche Forecast

Issued: Mar 2nd, 2013 9:32AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

The Columbias and Rockies will have one more day under a complex weather scenario but the ridge will begin to take hold late tomorrow.Overnight Saturday/Sunday:  Overnight will bring moderate precipitation amounts just before the cold front exits the region in the morning. The front will be trailed by a building ridge of high pressure that will bring much cooler and drier conditions under a light north-easterly flow.  Ridgetop winds will blow moderate from the NW. Alpine temperatures near -8 and freezing levels falling to 1000 m.Monday: Mainly dry, cooler conditions with clearing skies and the effects of solar radiation. Ridgetop winds will be light from the South. Alpine temperatures near -6 and freezing levels around 1000 m.On Tuesday and Wednesday a deep upper low over the eastern Pacific will push more snow from southerly directions over the southern half of BC again.

Avalanche Summary

A few skier triggered slab avalanches were  remotely triggered on Friday up to size 1.5, running far and fast. On Thursday, slab avalanches to size 1.5 were ski cut and failed naturally. Recent explosives testing in the southern portion of the region producing slab avalanches to size 2.5 isolated to the storm snow.

Snowpack Summary

30-60 cm of new snow has fallen adding to the ongoing storm snow instability. Strong SW winds have likely built wind slabs on lee slopes and terrain features.  The February 12th and 15th surface hoar layers now exist up to 100 cm below the surface and vary in distribution and reactivity. A buried sun crust may exist on solar aspects, and could also become reactive under the new load.A surface hoar layer buried on February 23 is still on the radar of some operators. This layer has been less likely to trigger by skiers, but may still be sensitive to large loads like avalanches in motion or cornice fall.The mid and lower snowpack are generally well settled and strong.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent new snow and wind have created new slabs, which may be particularly touchy on slopes in the lee of the wind. Rider triggering is likely.
Avoid exposure to overhead avalanche terrain, as large avalanches may run further then expected.>Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
Loading from new snow and wind may add reactivity to persistent buried surface hoar layers. In deeper snowfall areas, resulting avalanches may be large and destructive.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 6

Valid until: Mar 3rd, 2013 2:00PM

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