Avalanche Forecast

Issued: Mar 17th, 2015 9:15AM

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

Avalanche Canada pgoddard, Avalanche Canada

Winds have created a variable snowpack. Be alert to conditions that change with aspect and elevation.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Generally light precipitation is expected on Wednesday, with the freezing level around 1700 m and winds light to moderate from the S to SW. Moderate snow is expected on Thursday and Friday (15-20 cm /day) above about 1600 m (rain at lower elevations). Winds are moderate to strong from the S to SW.

Avalanche Summary

A skier accidentally triggered a size 3 hard wind slab on Monday, which failed on the March crust/facet layer. Skiers also remotely triggered size 1.5-2.5 slabs, most on northerly aspects, some of which failed on the crust/facet layer. A natural and human-triggered cycle of wind slabs was reported on Sunday.

Snowpack Summary

Wind slabs (most recently formed with northerly winds, but previously lee to the S-SW) and wind-affected surfaces are the main theme at the snow surface. Cornices may also be fragile. Older, buried wind slabs may be hard to spot. A crust/facet persistent weak layer, buried anywhere from 10 to 60 cm down, has started to play up (see avalanche summary). Avalanche problems associated with this layer may linger for a while. A deeper crust (formed by heavy rain in February) is down around 70 cm. Below the deeper crust, the snowpack is reported to be generally well-settled and strong. Below treeline, the diminishing snowpack is trending isothermal (same temperature throughout).

Problems

Wind Slabs

An icon showing Wind Slabs
Recent outflow winds left touchy wind slabs on lee terrain features. Cornices may also be fragile.
Give cornices a wide berth when travelling on or below ridges.>Travel on ridgetops to avoid wind slabs on slopes below.>Avoid lee or cross loaded slopes at or above treeline.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
People have been remote-triggering persistent slabs. The buried crust/facet layer could produce surprisingly large avalanches.
Choose well supported terrain without convexities.>Avoid thin, rocky or sparsely-treed slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Mar 18th, 2015 2:00PM

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