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Avalanche Forecast

Mar 6th, 2012–Mar 7th, 2012
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: Sea To Sky.

Intense solar radiation may cause a spike in avalanche activity on sun-exposed slopes.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Friday

Weather Forecast

Wednesday: Mostly clear with light winds and freezing levels rising to around 1200m. Thursday: Increasing high clouds throughout the day with light winds and freezing levels as high as 2500m for the southernmost part of the region. Friday: Mostly cloudy with snow increasing in the afternoon. Freezing levels around 1000m and moderate southwesterly winds.

Avalanche Summary

Reports from Monday include numerous Size 1-2 explosive-triggered and slope-cut soft wind slab avalanches. One of the larger slope-cuts stepped down 60cm to an old buried wind slab, while another failed on a crust buried last week and propagated onto 15 degree terrain. A brief period of strong solar radiation in the morning caused a couple of Size 3 loose snow avalanches on the Squamish-Cheakamus divide. These started off as surface sluffs and eventually entrained all of the recent storm snow on the entire slope and ran full path.

Snowpack Summary

Around 50-60cm of recent low density storm snow and/or weak wind slabs are bonding poorly to a variety of old snow surfaces, including crusts and wind slabs, from last week. Recent winds and precipitation patterns have created a highly variable slab depth with ability to propagate in low angled terrain and a structure conducive to step-down avalanches. The top 10cm or so is becoming moist during the day with sun exposure, and there is still a lot of snow available for reverse-loading if outflow winds pick up.

Avalanche Problems

Wind Slabs

Generally lurking below ridgecrests, behind terrain breaks, and in gullies. Wind slabs are sensitive to human triggers, and have the potential to step-down to deeper weaknesses and/or propagate into low-angled terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Storm Slabs

Touchy weaknesses within and under the recent storm snow are expected to become more reactive with sun-exposure. Cohesionless low-density snow overlying a crust can produce very large loose-snow avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 6