Avalanche Forecast

Issued: Dec 8th, 2015 5:12PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

The new snow has helped to improve the ski quality. More snow for Wednesday will add load to the existing weaknesses and we may start to see more avalanche activity before things cool off and snow subsides.

Summary

Weather Forecast

Tuesday's storm will taper off tonight, snowfall totals will be 10-25 cm. A smaller system starting around noon on Wednesday will bring 10-15 cm. FL will drop tonight and through Wednesday as the front passes. Winds will also drop to light with some strong gusts from the W-SW. No snow forecasted for the remainder of the week.

Snowpack Summary

The Dec 3rd interface is buried by 30-50 cm of snow and is a layer to watch right now. It consists of facets and large surface hoar below 2000m, wind effect in the alpine, and suncrusts on S & SW aspects. Moderate S & SW winds are building soft slabs in the lee of alpine features. The lower snowpack is well settled where the depth is close to 1 m.

Avalanche Summary

Small windslabs local to ridgecrests are reactive to skier traffic in the alpine and at treeline. Some cracking observed in a steep below treeline glade today where the Dec. 3rd surface hoar was present. Again, limited observations in the alpine due to poor visibility.

Confidence

Track of incoming weather systems is uncertain

Problems

Wind Slabs

15-40 cms of storm snow in the alpine and at treeline is being blown by moderate to strong S/ SW winds and forming windslabs in immediate lees of prominent features and ridgelines.

Be cautious as you transition into wind affected terrain.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Storm Slabs

20- 50 cm's of new snow is slowly settling into a cohesive slab. It will be most reactive in deeper snowpack areas where there is more than 30 cm's of new snow and below 2000m where it overlies the Dec. 3rd surface hoar or facets.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 9th, 2015 4:00PM