Avalanche Forecast

Issued: Feb 22nd, 2015 8:11AM

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

ghelgeson, Avalanche Canada

South Rockies.

Isolated pockets of wind slab in unusual locations may become more susceptible to human triggering as upper elevation temperatures warm Monday afternoon.

Summary

Confidence

Fair - Freezing levels are uncertain on Monday

Weather Forecast

Monday: Clear skies, light N winds, no precipitation, freezing level rising to 1700m. Tuesday: Increasing cloud cover, light W winds at valley bottom, strong NW winds at ridgetop. No precipitation, freezing level rising to 1500m. Tuesday Night: 5 to 10cm, freezing level at Valley Bottom. Wednesday: Broken skies, light variable winds, 1 to 2cm, freezing level at valley bottom.

Avalanche Summary

No new avalanches have been reported recently.

Snowpack Summary

Up to 10 cm of new snow may now cover a thick, solid crust that extents up to 2100m and firm wind pressed surface higher than that. The recent winds have been light to moderate from the northeast and I suspect that you may find isolated fresh wind slabs forming in reverse loaded lee features on southern aspects. Below 2100m the crust is effectively capping the snowpack and protecting a couple of buried persistent week layers. Two layers of surface hoar can be found down between 50 and 80cm. Recent snow pack test indicate that these layers are unlikely to fail but could propagate widely if they do. I suspect that at upper elevations where these layers are not protected by the surface crust it may still be possible to trigger an avalanche from a thin or rocky spot. The mid-December crust is becoming harder to find but where it does exist (mainly at treeline elevations) it is over a meter down.

Problems

Wind Slabs

Thin fresh wind slabs may be found in unusual locations. Potentially warm alpine temperatures Monday afternoon may increase the likelihood of human triggering.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious as you transition into wind affected terrain.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

Large avalanches are unlikely in most places but may be possible in the high alpine where a large trigger in a thin rocky spot could cause an avalanche on a buried persistent week layer.

Be aware of the potential for very large, deep avalanches due to the presence of buried surface hoar or a facet/crust layer.>Be alert to conditions that change with elevation, the surface crust that is protecting deeper weak layers tapers out in the high alpine.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 23rd, 2015 2:00PM