Avalanche Forecast

Issued: Mar 17th, 2013 10:47AM

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

pgoddard, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

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

Weather Forecast

Sunday night: Light snow. Light W winds. Alpine temperature near -9.Monday: Light snow (5-10 cm). Light W winds, gusting to strong NW. Alpine temperature near -5.Tuesday: No snow. Light to moderate SW winds. Alpine temperature near -3.Wednesday: Snow (10-15 cm). Moderate S winds. Alpine temperatures near -4.

Avalanche Summary

A few small sluffs were observed on Saturday as new snow began to show a poor bond to the crust below. I’d expect there was a lot more of this type of activity on Sunday.

Snowpack Summary

Around 30 cm of dry new snow arrived overnight Saturday/Sunday, which landed on a hard refrozen crust in most places (the exception possibly being very high elevation terrain). Strong NW winds are likely to have shifted this new snow into touchy wind slabs in the lee of terrain breaks. In non-wind affected steep terrain, sluffs may be running easily.Deeper in the snowpack, weak interfaces of surface hoar and/or crusts have become much less likely to be triggered now that they are capped by a supportive crust. However, until more information is gathered about the distribution and resilience of the crust, I’d keep these deeper weaknesses in the back of my mind, especially where they might be stressed by a very heavy load or triggered from a place where the crust above is not as strong (e.g. high elevation terrain or thin spots around rocks).

Problems

Wind Slabs

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

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

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.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

1 - 2

Valid until: Mar 18th, 2013 2:00PM