Avalanche Forecast

Issued: Mar 5th, 2014 8:48AM

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.

esharp, Avalanche Canada

South Rockies.

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The second in a pair of fronts will cross the region tonight or early Thursday before conditions become drier into the weekend.Tonight and Thursday: Periods of snow (up to 15cm) / Winds: moderate southwesterly gusting to strong / Freezing level: 1600mFriday: Sunny periods / Winds: moderate southwesterly / Freezing level: 1600mSaturday: Cloudy / Winds: moderate southwesterly / Freezing level: 1500m

Avalanche Summary

On Tuesday, we received a report of a natural storm slab avalanche and multiple human-triggered storm slab avalanches up to size 2 releasing down as deep as 35cm.

Snowpack Summary

30-45cm of new snow now overlies an old surface of surface hoar, a sun crust, and/or facets. Recent moderate to strong SW winds have created wind slabs in leeward and cross-loaded features. The midpack is broken by a persistent weak layer consisting of a crust, facets, and/or surface hoar that was buried mid February. In the thinner snowpack areas such as the Crowsnest and northern Elk Valley the layer can be found buried between 60 and 90 cm. In thicker areas such as the Flathead and around Fernie it may be found as deep as 150cm. This layer continues to show a high degree of sensitivity to human triggers especially in where it is buried closer to the surface. Check out the South Rockies Blog for a video discussing the persistent weak layer and the current avalanche problem. A weakness at the base of the snowpack may still exist in isolated areas of the region but triggering this layer is unlikely.

Problems

Storm Slabs

Accumulating storm snow is sitting on a weak layer of facets, surface hoar, and/or a sun crust. Strong SW wind has created stiff wind slabs in lee features.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

A buried persistent weak layer still has the potential to produce large and destructive avalanches especially in areas with a shallower snowpack where this layer can be found buried in the upper one meter.

Use conservative route selection, resist venturing out into complex terrain even if you observe no obvious signs of unstable snow.>Avoid unsupported slopes.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 6th, 2014 2:00PM