Avalanche Forecast

Issued: Nov 22nd, 2016 3:37PM

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

Avalanche Canada cam_c, Avalanche Canada

Danger is expected to increase with forecast snow and wind. As always, and especially when forecast confidence is low, it's important to supplement this forecast with your own observations. Please post your obs to the MIN.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

Snowfall starting overnight Tuesday is expected to continue throughout Wednesday with 10-15cm of fresh snow by Wednesday evening. Strong southerly ridgetop winds are expected at the onset of the storm before shifting to light to moderate southwesterlies for Wednesday. Another moderate system is expected to impact the area on Thursday, with a stronger system expected on Friday. Daytime high freezing levels are expected to hover around 1400 m throughout the forecast period.

Avalanche Summary

Reports from Monday include a remotely-triggered, 20-40 cm thick, Size 2 wind slab avalanche on a SE facing alpine slope in Rogers Pass. Check the Glacier National Park Avalanche Forecast for more details.

Snowpack Summary

Recent reports suggest snowpack depth is 150-200cm in the alpine and 100-170cm at treeline. The snowpack below treeline remains below threshold for avalanches, but watch out for early season hazards such as hidden rocks, stumps, and open creeks. 40-70cm of recent storm snow is settling into a cohesive slab over a hard crust. This crust is the primary weakness of concern and is expected to become increasingly reactive as the slab above settles and stiffens. Southerly winds have also formed very touchy wind slabs on lee features below ridetops in exposed terrain. Although conditions have been reported as being quite good, remember that an early season snowpack is inherently weak and requires thorough investigation before stepping out into bigger terrain.

Problems

Wind Slabs

An icon showing Wind Slabs
Touchy fresh wind slabs are 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.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Storm Slabs

An icon showing Storm Slabs
Recent storm snow is beginning to settle into a cohesive slab that is bonding poorly to a hard crust. On steep slopes the powder is also sluffing readily.
Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 23rd, 2016 2:00PM

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