Avalanche Forecast

Issued: Jan 29th, 2013 4:00PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Strong NW winds are forecasted to blow tonight, causing the danger to rise on Wed. In sheltered areas, and areas with insufficient new snow to blow around, the danger rating may be lower.

Summary

Weather Forecast

A northwesterly flow is bringing thin overcast skies, light precip and moderate to strong NW winds throughout the forecast period. Temperatures will gradually warm with alpine highs in the -5/-10 range and lows in the -10/-15 range.

Snowpack Summary

In alpine there is 20-25 cm of recent storm snow sitting on previous hard wind slabs and wind pressed snow. Some soft slab development in lee terrain near ridge tops. In shallow snow pack areas the mid-pack is facetting and losing strength.

Avalanche Summary

Forecasters observed a size 2 naturally triggered avalanche on a N aspect around 2300m on the Sunshine road. This avalanche was likely triggered by a cornice fall and likely occurred within the last 24 hours.

Confidence

Wind speed and direction is uncertain on Wednesday

Problems

Wind Slabs

Forecasted strong NW winds will create soft and hard slabs in areas where there is sufficient new snow to blow around (mainly in the southern and western parts of the forecast region).

Avoid areas with overhead hazard.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Hard slabs from previous high winds have been buried by recent storm snow. These slabs have been unreactive to skier triggering, but new wind loading may awaken them.

Be aware of the potential for wide propagations due to the presence of hard windslabs.Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Jan 30th, 2013 4:00PM