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Archived

Avalanche Forecast

Jan 3rd, 2012–Jan 4th, 2012
Alpine
5: Extreme
The avalanche danger rating in the alpine will be extreme
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high

Regions: Northwest Coastal.

A significant storm with heavy precipitation amounts and high freezing levels will result in a major avalanche cycle on Wednesday.

Confidence

Good - -1

Weather Forecast

An intense storm will bring heavy amounts of precipitation-expect around 25 mm Tuesday night and 30-40 mm on Wednesday. Freezing levels will rise to around 1500 m and then start to fall on Wednesday afternoon as a cold front passes over. The passage of the cold front will bring a further 10-20 mm precipitation for Thursday. Ridgetop winds will be extreme (up to 140 km/h) initially from the southwest, then becoming westerly. On Friday, another frontal system hits the coastal region bringing heavy precipitation near the coast and moderate amounts further inland.

Avalanche Summary

A few natural size 1-1.5 windslabs were observed in the last 24 hours near Stewart.A natural size 1.5 was observed below treeline near Terrace.

Snowpack Summary

The snow tap is still firmly on in this region, with almost continuous precipitation melding one layer of storm snow into the next. Sunday's storm added a further 45 cm of new snow to the ever increasing total; snow depths are currently at record levels for this time of year. Strong southwest to westerly winds have set up touchy windslabs on lee slopes. Large sensitive cornices exist. Expect further significant wind and storm slab development with the forecast weather.Previous weak layers in the midpack, including a surface hoar are gaining strength and becoming too deeply buried to be a concern except from very heavy loads (such as a cornice fall). The lower snowpack is generally well settled and strong.

Avalanche Problems

Storm Slabs

Large amounts of new snow with warming temperatures will create very touchy storm slab conditions.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely - Certain

Expected Size: 3 - 8

Wind Slabs

Extreme winds have set up touchy wind slabs that should be treated with the utmost respect.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 3 - 7

Deep Persistent Slabs

Deeply buried persistent weak layers have the potential to be triggered from rapid loading by large amounts of snow or rain and/or cornice falls.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 5 - 9