Avalanche Forecast

Issued: Mar 18th, 2013 10:46AM

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

pgoddard, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

Monday night: No snow. Moderate NW winds. Alpine temperature near -12.Tuesday: No snow. Sunshine. Light to moderate SW winds. Alpine temperature near -9.Wednesday: Heavy snow (20- 35 cm). Strong to extreme SW winds. Alpine temperature near -3.Thursday: Light snow. Light SW winds. Alpine temperature near -10.

Avalanche Summary

Numerous size 1-2 avalanches were triggered naturally, by skiers, explosives and vehicles on Sunday. In most cases, the new snow was failing on the hard crust below. Many were soft slabs where the wind had shifted the snow onto lee slopes, and several were loose dry avalanches.

Snowpack Summary

Around 20-30 cm of recent storm snow overlies a hard refrozen crust in most places. Strong variable winds have shifted this new snow into touchy wind slabs in the lee of terrain breaks. In non-wind affected steep terrain, sluffs are running easily.Deeper in the snowpack, weak surface hoar/crust interfaces have become much less likely to be triggered now that they are capped by a supportive rain crust. However, I’d remain wary of any spots where the crust above is not as strong.

Problems

Wind Slabs

Be alert for wind slabs behind ridges and terrain breaks. Cornices may be touchy too.

Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Loose Dry

New snow is likely to slide easily on a buried crust. It may have enough force to trip you up or carry you into a terrain trap.

On steep slopes, pull over periodically or cut into a new line to manage sluffing.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

Be wary of travelling on or below steep slopes which are being warmed by direct sun. Storm snow may fail naturally with the influence of solar radiation.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Pay attention to overhead hazards.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 19th, 2013 2:00PM