Avalanche Forecast

Issued: Feb 28th, 2013 9:15AM

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

Avalanche Canada pgoddard, Avalanche Canada

Summary

Confidence

Fair - Track of incoming weather is uncertain for the entire period

Weather Forecast

Thursday night/ Friday: Moderate to heavy precipitation. Strong to extreme SW winds. Freezing level around 1500-1800 m.Saturday: Light to moderate precipitation. Winds easing to moderate southerly. Freezing level around 1800 m, falling to 1000 m.Sunday: Lingering snow showers could bring up to 15 cm snow, then clearing up. Light winds. Freezing level around 1000 m.

Avalanche Summary

Recent reports include several human-triggered slab avalanches to size 2, involving wind slabs, recent storm snow weaknesses and the persistent weakness buried last week. Some events involving the persistent weakness were remotely triggered from as far as 50 m away. A size 3 slab failed naturally on the persistent weakness, wrapping around an entire north-facing bowl and running across a flat bench. A size 2.5 avalanche was triggered by a party of sledders on Sunday in the Brohm Ridge area, and left a man buried 1.8 metres below the surface. Check out the Forecaster blog for the full story. Activity seems to have slowed on Wednesday, but intense storm loading is expected to drive another avalanche cycle over the next few days.

Snowpack Summary

A potentially volatile weakness of surface hoar and/or a crust exists within the upper metre or so of the snowpack. Add an intense storm, with heavy precipitation rates, warming and very strong winds, and we have a good recipe for widespread avalanche activity. The lower snowpack is well settled.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm snow is expected to become very touchy with continuous loading throughout the forecast period, especially where wind-loaded. Storm slabs may step down to persistent weaknesses, creating very large avalanches
Avoid all avalanche terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Certain

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
Persistent weaknesses buried last week demand respect, as they are very touchy and are causing surprisingly large avalanches.
Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 7

Valid until: Mar 1st, 2013 2:00PM

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