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Archived

Avalanche Forecast

Dec 14th, 2012–Dec 15th, 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
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
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

Regions: South Coast.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Synopsis: A series of frontal systems bringing moderate to heavy snowfall and strong winds will affect the South Coast for the next few days.Saturday: Moderate snow – 10-15 cm. Winds increase to strong from the SW. The freezing level should remain near valley bottom. Sunday: A short break early in the day, then moderate to heavy snow overnight and into Monday (~10-15 cm). Winds increasing to strong from the SW with the arrival of the system. Freezing level near valley bottom. Monday: Heavy snow (primarily in southern areas). Freezing level could jump to 800 m.

Avalanche Summary

There were a few reports of small natural and human triggered loose snow avalanches on Wednesday and Thursday. Recent reports include evidence of previous large avalanches, including one from Mt Joffre at 2000m and the east face of Cayoosh Mountain in the Duffy Lake area last weekend (check out Wayne Flann's Avalanche Blog for a photo of the Cayoosh avalanche).

Snowpack Summary

Approximately 10 cm of new snow may have buried a thin layer of surface hoar in some areas. Moderate westerly winds have probably redistributed low density snow into soft wind slabs in exposed lee terrain. The late November surface hoar has been found down 70-90 cm but produces inconsistent results with snowpack testing. A well settled and rounding mid-pack is overlaying the early November crust, which continues to give occasional sudden planer compression test result in the overlying facets. Meanwhile in the Coquihalla area, recent reports suggest an overall well settled "right side up" (progressively more dense with depth) snowpack. The early November crust has not been found in the Coquihalla, although we don't have any reports from the high alpine. Conditions may be quite different in the Northern part of this region, please email us your observations if you are out in the field. [email protected]

Avalanche Problems

Wind Slabs

Weak wind slabs may be encountered below ridge crests, behind terrain features and in cross-loaded gullies.
Avoid lee and cross-loaded terrain near ridge crests.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Persistent Slabs

Watch for slopes that roll over such that the slab is unsupported from below. Particularly in areas with a shallower snowpack.
Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5