Avalanche Forecast

Issued: Dec 12th, 2012 9:22AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada ccampbell, Avalanche Canada

Summary

Confidence

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

Weather Forecast

Thursday: Cloudy with light snow starting in the afternoon, freezing levels rising as high as 500m and moderate westerly  winds becoming strong southwesterlies with the onset of precipitation. Friday: Snow easing throughout the day with 10-15cm total since Thursday, moderate northwesterly winds and freezing levels as high as 500m. Saturday: Moderate to heavy snowfall, extreme southwesterly winds and freezing levels rising as high as 1000m.

Avalanche Summary

Recent reports include evidence of previous large avalanches from Mt Joffre at 2000m and the east face of Cayoosh Mtn in the Duffy Lake area (check out Wayne Flann's Avalanche Blog for a photo of the Cayoosh avalanche). Glide cracks are getting big and releasing to Size 2, and ski cutting has been producing heavy sluffs.

Snowpack Summary

A recent Rutschblock test at 2100m on a north aspect above Duffy Lake gave an RB3 whole block release down 30cm on a storm snow weakness. The late November surface hoar was found down 70cm but so far has been unreactive to snowpack testing. A well settled and rounding mid-pack is overlaying the early November crust, which gave a moderate 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 low density surface snow is causing a lot of sluffing in steeper terrain, but not reacting as a slab. Conditions may be quite different in the Northern part of the region, please email us your observations if you are out in the field. forecaster@avalanche.ca

Problems

Wind Slabs

An icon showing Wind Slabs
Weak wind slabs may be encountered below ridge crests, behind terrain features and in cross-loaded gullies. Be especially diligent as northerly winds start to reverse load unusual aspects.
Be cautious as you transition into wind affected terrain.>Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Slopes that roll over such that the slab is unsupported from below. Particularly in areas with a shallower snowpack.
Choose well supported terrain without convexities.>Make observations and assess conditions continually as you travel.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Dec 13th, 2012 2:00PM

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