Avalanche Forecast

Issued: Jan 18th, 2013 9:39AM

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.

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Inverted temperatures. Below freezing at valley bottom, slightly above freezing in the alpine. Strong ridgetop winds out of the NW. No precip expected.Sunday: Freezing level starts at valley bottom, rises to 1000m during the day. Winds start strong out of the NW, backing down to moderate by dinner time. Trace of snow in the morning.Monday: Below freezing at valley bottom, slightly above freezing in the alpine. Ridgetop winds mod/strong west. No precip expected.

Avalanche Summary

A few loose snow avalanches to size one occurring on upper elevation S, SW and even NE facing slopes were reported Wednesday.

Snowpack Summary

Intense recent winds have redistributed snow and created large cornices. The snow surface is now a mix of sastrugi, hard slab and soft slab in open areas. With the warm temps, slopes receiving direct sun are moistening in the afternoon. Surface hoar is continuing to form in protected areas too. Below this around 60cm of settled snow rests on a myriad of old surfaces (January 4th interface) that include sun crust on steep south and west facing terrain, surface hoar in sheltered locations at treeline and below and facets everywhere else. Reports indicate that this bond has strengthened over time and is now fairly tight. The overlying slab has also settled significantly. The bond at this interface seems to have strengthened somewhat with time. The overlying slab has also settled significantly. There are some reports of glide cracks on Mt Fernie, these mysterious phenomena should be given a wide berth.

Problems

Wind Slabs

Strong to extreme winds out of the W/NW have left hard slabs, soft slabs, sastrugi and potentially unstable cornices in their wake. Watch for wind slabs behind midslope features like ridges and ribs. Be alert for wind slabs in unusual locations.

Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>Cornices are large and may become unstable with the warm alpine temps. Avoid traveling on or below them.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

While unlikely, slopes that didn't slide in the last avalanche cycle may still be of concern this weekend. Triggering is most likely in areas that go from thick to thin in steep unsupported terrain.

Conditions are greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 5

Valid until: Jan 19th, 2013 2:00PM