Avalanche Forecast

Issued: Mar 5th, 2014 9:01AM

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

esharp, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair

Weather Forecast

The second in a pair of frontal systems will cross the region Wednesday night or early Thursday. There is some uncertainty with the forecast freezing levels which may be lower than those listed below.Tonight and Thursday: Periods of snow (up to 20cm) / Winds: moderate southwesterly gusting to strong / Freezing level: 1500mFriday: Flurries / Winds: moderate southwesterly / Freezing level: 1300mSaturday: Flurries / Winds: moderate southwesterly / Freezing level: 2000m

Avalanche Summary

The storm slab has become increasing reactive producing avalanches up to size 2.Avalanche activity on the mid pack's persistent weak layer has decreased recently indicating that it is has become harder to trigger. However the few avalanches that have released on this layer have been large and destructive avalanches. Some have been triggered remotely.

Snowpack Summary

Up to 50cm of new storm snow sits on top of a variety of old surfaces. A layer of facets can be found on north aspects with a sun crust on many south facing slopes. In sheltered and shaded features surface hoar can be found. Warming temperatures are causing this new snow to settle into a widespread soft slab. Sustained SW winds have have formed winds slabs in lee features.The midpack is broken by a widespread persistent weak layer buried mid February and now down 90 to 120cm. The form of this week layer varies from surface hoar to a sun crust and/or facets. It can be found at all elevations, on all aspects and is still a concern.

Problems

Storm Slabs

New snowfall is settling into a storm slab which overlies a variety of potentially weak surfaces. Moderate to strong SW winds have formed stiff wind slabs in lee features which will be more sensitive to human triggers.

The new snow will require several days to settle and stabilize.>Avoid open slopes with any steepness over 30 degrees.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 4

Persistent Slabs

The mid-Feb weak layer still remains reactive in some areas and has the potential to produce large, destructive avalanches. The increasing load of the new snow may 'wake up' this weak layer and very large natural avalanches are possible

Avoid unsupported slopes.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

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