Avalanche Forecast

Issued: Apr 3rd, 2012 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs, Loose Wet, Persistent Slabs and Cornices.

jeremy.mackenzie, Alberta Parks

Kananaskis.

An intense storm is expected on Wednesday with precip beginning as rain below 2000m and then switching to snow as the temps cool. Rapid changes will occur in avalanche danger with heavy loading due to snow, wind and rain. Pay attention to conditions!

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

A significant storm is expected to arrive Wednesday morning with more than 25cm possible. This precipitation may start as rain below 2000m and then switch to snow as the temperatures drop through the day. Winds will switch to the north late in the day Wednesday, before swapping back to the traditional SW on Thursday.

Avalanche Summary

A few small loose dry sluffs were observed in steep lee alpine terrain. Isolated snowballing on solar aspects was observed by mid afternoon.

Snowpack Summary

The snowpack is settling with the warm temperatures. Sun crusts are forming and melting on solar aspects as the days heat up. Strong SW winds at ridgetop continue to add to recent wind slab development at alpine and treeline elevations. Wind slabs remain touchy, with an average of 40cm sitting on a variety of surfaces, the most concerning being previously formed crusts.

Problems

Storm Slabs

Storm slabs will form with the incoming weather on Wednesday adding to the already sensitive wind slabs. The current slabs are averaging 40cm deep and sit on a crust in many locations. Slides may step down as recent avalanche activity has proven.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Loose Wet

Heavy wet snow and rain will start the day on Wednesday and could begin an avalanche cycle at low elevations. These slides could step down and trigger a deeper weak layer.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

The February surface hoar is buried 120-150cm at treeline. This interface is still hard to trigger, but it has come back alive in recent cornice triggered avalanches. The spring transition could see more avalanches stepping down to this layer.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 6

Cornices

Cornices are large and have been failing with additional load and/or solar radiation. Cornice chunks themselves are a problem, and several failures have cause large avalanches by triggering the Feb surface hoar or the basal facets.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Apr 4th, 2012 9:00AM