Avalanche Forecast

Issued: Feb 14th, 2015 8:03AM

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

triley, Avalanche Canada

South Rockies.

A Special Public Avalanche Warning is in effect for this region. The cooling trend is expected to begin overnight, but daytime heating and strong solar radiation may continue.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Expect cloud and some lingering precipitation overnight. Freezing level should be near valley bottom by Sunday morning. Light winds and a mix of sun and cloud on Sunday with freezing levels rising up to about 1500 metres. Cloudy overnight and Monday with light winds and freezing down to valley bottoms followed by daytime heating up to 1200 metres. Tuesday should start with a good freeze and then freezing levels will rise up to about 1500 metres under clear skies with strong solar radiation.

Avalanche Summary

No new avalanches reported.

Snowpack Summary

Recent reports suggest 10-50 cm thick hard wind slabs lurk below ridge crests and behind terrain features at treeline and alpine elevations; however, these seem to be generally well-bonded. In more sheltered areas, variable amounts of previous storm snow is sitting on a crust that formed at the end of January. Recent warm temperatures have softened the upper snowpack, reawakening deep persistent weaknesses in isolated areas. As temperatures continue to fluctuate and stress the snowpack, expect an increased likelihood of triggering large destructive avalanches in isolated areas (e.g. thin spots) with heavy triggers (e.g. cornice falls, stuck sleds spinning tracks, or groups of people).

Problems

Wind Slabs

Hard wind slabs may be stubborn to trigger, but they have a tenancy to propagate across entire slopes or pull into low angled terrain on ridge crests, catching people by surprise.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>Be cautious as you transition into wind affected terrain.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Cornices

Cornices will likely become unstable with fluctuating temperatures. Not only are they a hazard in themselves, but they are also large triggers for deep slab avalanches on the slope below.

Give cornices a wide berth when travelling on or below ridges.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

Persistent weaknesses recently woke up with the warm temperatures and should be treated with suspicion until after things freeze up again. Although likely to need a large trigger, the potential consequences are dire.

Be aware of the potential for very large, deep avalanches due to the presence of buried surface hoar or a facet/crust layer.>Avoid steep convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Feb 15th, 2015 2:00PM