Avalanche Forecast

Issued: Feb 23rd, 2015 8:46AM

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.

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Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Tuesday: A lingering above freezing layer of warm air may persist between 1700m and 3000m through the day Tuesday. Strong NW winds at ridgetop, light SW at treeline. No precipitation. Tuesday Night: 1cm to 10cm of snow, freezing level decreasing to valley bottom by nights end. Wednesday: Increasing cloud cover, winds decreasing to light NW throughout the day, no precipitation, freezing level at valley bottom. Thursday: Broken skies, light variable winds at all elevations, no significant precipitation, 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

Strong NW winds may create isolated pockets of wind slab in wind exposed features Tuesday. It's important to factor these small but potentially touchy wind slabs into your travel plan for the day, especially if you're in complex terrain.

Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Use ridges or ribs to avoid pockets of wind loaded snow.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

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

Elevations: Alpine, Treeline.

Likelihood

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 24th, 2015 2:00PM