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Archived

Avalanche Forecast

Feb 17th, 2014–Feb 18th, 2014
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Coast.

Confidence

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

Weather Forecast

The next Pacific frontal system will cross the South Coast regions on Tuesday resulting in strong wind and precipitation. Generally unsettled conditions are expected for Wednesday and Thursday with light intermittent snowfall and sunny breaks.Tuesday: Snowfall 20-30cm, afternoon freezing levels around 1000m, ridgetop winds 50-70km/h SWWednesday: A mix of sun and cloud, light intermittent snowfall 1-3cm, afternoon freezing levels around 700m, ridgetop winds 30-50km/h WThursday: Cloudy with sunny breaks, light intermittent snowfall 2-4cm, afternoon freezing levels around 700m, ridgetop winds 30-50km/h NW

Avalanche Summary

On Saturday skiers recreating in the Coquihalla area triggered a size 2 slab avalanche on a steep slope in open trees, below treeline. One partial burial occurred, sustaining some injury. One natural cornice release triggered a size 2.5 slab avalanche on the slope below and explosives control produced numerous 2.5-3.5 avalanches. Nothing was reported from the region on Sunday but this may be due to a lack of observers.  It is expected with the large amount of new snow over Sunday night that natural storm slab avalanches likely occurred on Monday.

Snowpack Summary

In the last week, the Northern parts of the region have received over 1m of new snowfall and the Southern areas have seen over 1.5m. This snow has settled into storm slabs which are typically 50-70cm thick in the north and 80-120cm in the south. This storm slab overlies a variety of old surfaces consisting of facets, surface hoar, a scoured crust, wind press, or any combination of these. Particularly of concern is the combination of buried facets on a crust being unusually reactive at treeline and below treeline elevations. Whumpfing and widespread avalanche activity further indicate a poor bond between the new snow and these old surfaces.Strong to extreme winds are shifting the new snow into deeper, reactive wind slabs in leeward terrain.The mid and lower snowpack are generally strong and well-settled. Although basal facets and depth hoar are likely to exist in the north of the region.

Avalanche Problems

Storm Slabs

An abundance of new snow has built a very touchy storm slab which is reactive at all elevations. The poor bond on a variety of old weak interfaces creates the perfect recipe for dangerous avalanche conditions. Thicker wind slabs exist on lee slopes.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Stick to simple terrain and be aware of what is above you at all times.>Use caution in lee areas in the alpine and treeline. Recent wind loading have created wind slabs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 2 - 5