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Archived

Avalanche Forecast

Mar 20th, 2013–Mar 21st, 2013
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Confidence

Fair

Weather Forecast

Synopsis: A strong low pressure system today with wind and mild temperatures is followed by a cool and unsettled air mass through Friday. Conditions will become gradually less windy and less convective but stay generally cooler than normal for the period. Saturday and Sunday the cool north/northwesterly flow will dry out as a ridge of high pressure is very slowly approaching the regions.Wednesday Night: Freezing Level: Valley Bottom Precip: 10/15mm – 10/25cm Wind: Moderate WestThursday: Freezing Level: 900m Precip: 3/6mm – 5/10cm Wind: Moderate W gusting Strong NW Friday: Freezing Level: 1100m Precip: 3/6mm – 5/10cm Wind: Light gusting strong NorthSaturday: Freezing Level: 800m No significant precip expected.  Wind: Light, North

Avalanche Summary

Tuesday was filled with reports of slufing to size 1 on steep features. In the past few days numerous size 1-2 avalanches have been triggered naturally, by skiers, explosives and vehicles. In most cases, the new snow was failing on the hard (March 16th) crust below. Many were soft slabs where the wind had shifted the snow onto lee slopes, and several were loose dry avalanches.

Snowpack Summary

The KB snowpack structure is a bit complex right now.  Wednesdays storm snow is accumulating on a thin crust that developed on all aspects with the exception of due north on Tuesday.  A thick supportive crust that professionals have dubbed the March 16th crust can be found down 30 - 50 cm.  A buried persistent weakness from March 10th is down approximately 60 cm. This surface hoar/sun-crust combo continues to fail in a sudden planar fashion when tested. Cornices are large and fragile.

Avalanche Problems

Storm Slabs

Wednesdays storm snow will be easily transported by forecasted strong W/NW winds Wednesday night into Thursday.  Fresh sensitive wind slabs will be a problem on wind exposed slopes at both alpine and tree line elevations. 
Good day to make conservative terrain choices.>Avoid freshly wind loaded features.>The new snow will require a couple of days to settle out and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 6