Avalanche Forecast

Issued: Mar 18th, 2013 8:23AM

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

ali haeri, Parks Canada

Glacier.

Slab and loose avalanches can be easily triggered by riders today with fresh snow overtop a crust.

Summary

Weather Forecast

Unsettled moist weather pattern producing convective storms with light to locally moderate amounts. A brief ridge of high pressure on Tuesday keeping things dry with sunny skies before a Pacific frontal system arrives on Wednesday bringing moderate amounts of precipitation.

Snowpack Summary

30cm of low density snow over the Mar 16th crust of varying thickness depending on elevation below 2000m. Moist snow below the crust. This overlies a well settled mid pack. The Feb 12 SH is down around 100-150cm.

Avalanche Summary

Several skier triggered avalanches in the Hermit area yesterday to size 1.0. These were low density slabs sliding on a crust down 15cm with surprisingly wide propagation running far and fast.7 natural slab avalanches in the highway corridor ranging in size from 2.0 to 2.5

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Wednesday

Problems

Storm Slabs

A buried rain crust is providing an ideal bed surface for new snow avalanches below 2000m. There's around 30cm overtop and was really reactive yesterday to rider triggering with wide propagation, running far and fast.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

Moderate south winds and new snow available for transport mean that you could expect windslabs on lee terrain above treeline.

Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

It will likely take a large trigger, like a cornice or another avalanche to trigger the surface hoar/crust layer from February down 1-1.5m. The resulting avalanche would be very large and destructive if triggered.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

Valid until: Mar 19th, 2013 8:00AM