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Archived

Avalanche Forecast

Mar 8th, 2013–Mar 9th, 2013
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
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
1: Low
The avalanche danger rating below treeline will be low
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
1: Low
The avalanche danger rating below treeline will be low

Regions: South Rockies.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

The ridge of high pressure moves south eastward over the South Rockies bringing mostly clear skies for Saturday.  The timing of the next wave of moisture from the return of a more westerly zonal flow is uncertain. Current models suggest Monday mid day.  Overnight into Saturday:  Mostly clear skies with the possibility of some morning fog patches.  Light winds out of the north west at ridge top are expected and freezing levels could rise to 1800 m with the influence of some warmer air.  Sunday:  Cloudy with sunny breaks, chance of light precipitation. Alpine temperatures near -7.0.  Winds increasing, moderate to strong from the west.Monday:  Timing of the next system is uncertain, but some models are showing light to moderate snowfall amounts for the region by later Monday.

Avalanche Summary

A natural cycle of loose and soft slab avalanches up to size 1.5 occurred Thursday and into Friday throughout the forecast region.  An out of bounds skier near Castle Mtn triggered a size 2 slab avalanche in steep north east facing terrain on Gravenstafel Ridge on Thursday.

Snowpack Summary

Approximately 30 cm of low density snow has fallen in the last 48hrs. Greatest accumulations have occurred in the Elk Valley South and Flathead regions, while areas such as Elk Valley North and Crowsnest pass may not have seen as much new snow.  Southwest winds have contributed to cornice growth and soft slab formation in open areas in the alpine and treeline. The recent snow accumulations add to the variable amounts of settled storm snow that overlies a widespread melt freeze crust.  This supportive crust exists up to about 2000m in elevation in much of the forecast area. The mid and lower pack are strong and well settled.

Avalanche Problems

Storm Slabs

Soft slabs have formed at upper elevations with recent settlement and wind transport. Warmer temps and direct sun may cause slabs to become more reactive to human triggering.
Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Loose Wet

Potential for wet loose snow activity will increase as recent storm snow receives direct sun.
Watch for wet loose or slab activity with forecast warm temperatures.>

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 4

Cornices

Cornices have grown with recent snowfall and southwest winds.  The chance of cornice fall may increase with warm temperatures and direct sun, and could also trigger slab avalanches below.
Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 5