Avalanche Forecast

Issued: Mar 28th, 2014 9:30AM

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

mbender, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Sunday

Weather Forecast

Saturday: Light to locally moderate snowfall overnight Friday into Saturday. Freezing level 1600m. Winds light southwest.Sunday: Cloudy with light to locally moderate amounts of snow possible. Freezing level rising to 1800m. winds light west.Monday: Scattered flurries. Freezing level 1500. Winds light to moderate west.

Avalanche Summary

Recent reports from the central part of the region (where the most recent snowfall was intensified) indicate natural and explosives triggered avalanches running in the alpine to size 2.5 on all aspects. These were isolated to the most recent storm snow.

Snowpack Summary

5-40cm of new snow has fallen in the region (5-10 in the north and up to 40 in the central). This new snow is settling and likely being formed into soft wind slabs immediately lee of ridge crests. Moist snowNumerous crusts can be found in the upper 60cm of the snowpack on south facing slopes. The March 15 crust/surface hoar interface is down 50-80cm. Down90-120cm below the surface you may find surface hoar and crusts buried at the beginning of March. This interface is still touchy in some areas, particularly in the north of the region. It also continues to produce sudden planar failures in compression tests.The deeper facet/crust persistent weakness buried at the beginning of February, now down 120 - 200cm, still seems to be reactive and should not be trusted. Needless to say, any avalanche at these deeper, persistent interfaces would be large and destructive. Weak basal facets exist in many areas, but without a large load, triggering is unlikely.

Problems

Wind Slabs

Recent accumulations have likely been blown into pockets of wind slab by generally moderate southwest winds.

Stay well to the windward side of corniced ridges.>Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

There are a number of persistent layers in the mid to lower snowpack which have professional operators concerned. Possible triggers include cornice fall, thin spot triggering and/or solar warming.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Mar 29th, 2014 2:00PM