Avalanche Forecast

Issued: Nov 24th, 2011 8:55AM

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

ccampbell, Avalanche Canada

Northwest Coastal.

Avalanche danger is expected to remain HIGH as long as the intense storms continue.

Summary

Confidence

Poor - Due to limited field observationsfor the entire period

Weather Forecast

Friday: Light to moderate precipitation increasing intensity throughout the day with 10-20cm expected by the evening. Strong westerly winds becoming extreme southerlies, and freezing levels around 600m. Saturday: Heavy precipitation, extreme southwesterly winds and freezing levels as high as 1000m. Total accumulation expected to be in the 50-75cm range by Sunday morning. Sunday: Freezing levels drop, winds calm down and shift to westerly, and precipitation eases off throughout the day as the storm blows over.

Avalanche Summary

Recent observations are limited, but I suspect natural avalanche activity occurred and will continue in response to heavy loading from snow and especially wind.

Snowpack Summary

Most areas received over a metre of new snow since the weekend, and it's still snowing. Fluctuating freezing levels and varying precipitation intensity and wind throughout the recent storms has probably resulted in various weaknesses within upper snowpack. Widespread large surface hoar was also observed on the previous snow surface at all elevations. The mid and lower snowpack is generally well settled and strong with an old rain crust near the ground.

Problems

Wind Slabs

Weak wind slabs are probably lurking well below ridge crests, behind terrain breaks, and in cross-loaded gullies. Natural avalanche activity probably occurred and is expected to continue in response to heavy loading from snow and wind.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Storm Slabs

Storm slabs are likely very touchy, especially where they are sitting on surface hoar.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Nov 25th, 2011 8:00AM