Avalanche Forecast

Issued: Nov 26th, 2012 8:23AM

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.

mike.koppang, Alberta Parks

Kananaskis.

Sporadic large avalanche activity continues to occur. See avalanche tab for info on reported large slide in Rae Glacier area. The November rain crust will remain a layer of concern for some time. JM

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

The NW flow will slowly change to a W and then a SW flow by Wednesday night. Light snow is expected to begin Wednesday night. Significant amounts of loose dry snow are available for wind transport so increasing winds may increase avalanche danger ratings in the Alpine as the week progresses.

Avalanche Summary

Report came into the office this afternoon of a size 2.0 avalanche in the Rae Glacier area and a larger avalanche, two to three days old in the same area. This larger avalanche was described as on a N aspect at 2600m with a fracture depth of 200cm. No other details are available at this time.

Snowpack Summary

The snowpack is settling. Some wind transport is still occurring at ridgetop. November rain crust continues to be a concern for step down potential of persistent slab above.

Problems

Wind Slabs

Pockets of wind slab are present in lee and cross loaded features in the alpine and isolated areas at treeline. NW winds over the past 2 days are loading S and SE aspects. Cornice collapses have triggered slabs up to sz 2.5 on underlying slopes.

Avoid lee and cross-loaded terrain near ridge crests.>Avoid steep slopes below cornices.>Be very cautious with gully features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

The Nov rain crust persists about 15cm off the ground throughout the forecast area. Avalanches in the upper snowpack may step down to this weakness. Recent report of a large avalanche on the Rae Glacier, likely stepped down to the Nov rain crust.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Whumpfing is direct evidence of a buried instability.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Nov 27th, 2012 2:00PM