Avalanche Forecast

Issued: Mar 8th, 2013 9:28AM

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

slemieux, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

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

Weather Forecast

Friday night and Saturday: The dominating feature is a ridge of high pressure over the whole province bringing warmer air (-1 in the alpine), freezing levels rising to 1700 m., clear skies and light NW winds. Sunday: The ridge is breaking down in the North and remains in the Southern part of the interior range. There is a chance of light precipitation for Sunday (5-10 mm) with winds picking up in the moderate range from the W. Temperatures are slightly cooler than Saturday.Monday: Another system which could deliver more precipitation is expected for Monday but the timing and intensity is still uncertain.

Avalanche Summary

Several soft slabs size 1 and 1.5 were triggered by skiers in the new snow (20-30 cm deep) and was running on the underlying crust or on the older snow interface. There was also several reports of sluffing in steep terrain.

Snowpack Summary

Warm temperatures and solar radiation forecasted for tomorrow will weaken the surface layer possibly triggering the recent storm slab (between 20-30 cm deep). This recent snow is sitting on an older snow interface above 2000 m. and on a melt freeze crust below that elevation. In much of the region, up to 80 cm snow overlies fairly well preserved surface hoar and sun crust. This interface is still producing sudden collapse results during snow tests. A cornice fall or an avalanche in the storm snow could definitely trigger this deeper instability, especially where the melt freeze crust does not exist above 2000 m.

Problems

Storm Slabs

Up to 30 cm of recent snow is sitting on a melt freeze crust and has formed touchy storm slabs.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Travel one person at a time on all slopes capable of producing an avalanche.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

The 80 cm deep surface hoar/sun crust weak layer could be triggered by a cornice fall or an avalanche stepping down from the storm snow. Be aware of the sun and warmth weakening the snowpack and cornices.

Avoid steep slopes below cornices.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Loose Wet

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Sluffs may trigger deeper instabilities.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Mar 9th, 2013 2:00PM