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Avalanche Forecast

Nov 22nd, 2016–Nov 23rd, 2016
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: North Columbia.

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.

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.

Avalanche Problems

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

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