Avalanche Forecast

Issued: Nov 26th, 2016 4:59PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Wind Slabs and Storm Slabs.

cgarritty, Avalanche Canada

Purcells.

New snow has increased avalanche danger in the region. Stick to conservative terrain until the snowpack stabilizes.

Summary

Confidence

Weather Forecast

40cm of new snow fell in the north of the region over Friday and Saturday while winds have eased to light and shifted from southwesterly to easterly. Isolated lingering flurries are expected on Sunday with cooling temperatures and light winds shifting to northwesterly. A continued drying and cooling trend is expected Monday and Tuesday.

Avalanche Summary

A report of a small cornice failure triggering a size 1 storm slab at treeline can be found on the MIN. Another MIN report from Tuesday details a natural Size 2 storm slab avalanche on a steep fan below a large alpine face in the Glacier Creek area. New and continued snowfall is increasing concerns for touchy slabs and cornices forming at higher elevations and in exposed terrain.

Snowpack Summary

Up to 40cm of new snow has fallen in the past 48 hours. Moderate to strong winds that accompanied the snowfall have contributed to the touchy cornices and wind slabs forming at treeline and above. The storm snow since Nov 13 has now accumulated to 60+cm and has settled into a cohesive slab over the hard November 13 crust. 6mm surface hoar has been observed above the crust on north aspects at higher elevations and has yielded easy to moderate snowpack test results. Total snowpack depth has exceeded one metre in the North Purcells. The snowpack below treeline is creeping toward threshold for avalanches, but early season hazards such as hidden rocks, stumps, and open creeks remain the primary hazard here.

Problems

Wind Slabs

New snow is building touchy wind slabs. These are primed for triggering on the downwind side of ridgecrests in exposed areas.

Avoid steep or convex lee features directly below ridgetops.Avoid areas where the snow feels stiff or 'slabby'.Travel on ridgetops to avoid wind slabs on slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Storm Slabs

New snow is settling into a cohesive slab that may be bonding poorly to a hard crust or surface hoar. Increased load from new snow will increase the likelihood of triggering deep instabilities.

Minimize exposure during periods of heavy loading from new snow and wind.Carefully assess the bond to the crust before committing to a slope.Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 27th, 2016 2:00PM