Avalanche Forecast

Issued: Nov 25th, 2016 3:00PM

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.

Avalanche Canada cgarritty, Avalanche Canada

Heavy snow is forecasted for the North Purcells on Saturday. Exercise extra caution during and after the storm.

Summary

Confidence

-

Weather Forecast

20-25cm of new snow fell yesterday and overnight under the influence of light to moderate winds that trended from SE to SW and increased to gusts of 30km/h this morning. Up to 25cm of new snow is expected to fall in the north of the region on Saturday under light winds and a freezing level rising from 500m to 1000m. Southern parts of the region are expected to receive only trace amounts of new snow.

Avalanche Summary

Recent and forecasted snowfall are amplifying concerns for slabs and cornices forming at higher elevations and in exposed terrain. Recent reports include a natural Size 2 storm slab avalanche on a steep fan below a large alpine face in the Glacier Creek area. Check out the MIN report for for details including a photo.

Snowpack Summary

Snowfall from yesterday and overnight totaled 20-25 cm and contributed to a highly variable HS reported at 80-150cm yesterday. The new snowfall was accompanied by light to moderate winds, which will promote the growth of both cornices and touchy wind slabs that already exist in the region. Storm snow since Nov 13 has now accumulated to 60+cm and is settling into a cohesive slab over the hard Nov 13 CR. This crust is the primary weakness of concern and is expected to become increasingly reactive as the slab above settles and stiffens. Buried surface hoar has also been reported down 40cm on north aspects at upper treeline elevations, where it gave easy to moderate snowpack test results. 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

An icon showing Wind Slabs
Touchy wind slabs are growing and primed for triggering on the downwind side of ridgecrests in exposed areas.
Travel on ridgetops to avoid wind slabs on slopes below.Avoid areas where the snow feels stiff or 'slabby'.Avoid steep or convex lee features directly below ridgetops.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Storm Slabs

An icon showing Storm Slabs
Recent storm snow is beginning to settle into a cohesive slab that may be bonding poorly to a hard crust or surface hoar. Forecasted snowfall will increase the size and sensitivity of storm slabs.
Be cautious of sluffing in steep terrain.Carefully assess the bond to the crust before committing to a slope.Minimize exposure during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Nov 26th, 2016 2:00PM

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