Avalanche Forecast

Issued: Jan 1st, 2012 9:32AM

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

Avalanche Canada ghelgeson, Avalanche Canada

Summary

Confidence

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

Weather Forecast

Warm air enters the region late Sunday persisting through mid-day Monday. Freezing levels are forecast to be between 1500 - 2000 m & winds in the alpine will be ripping out of SW @ 55 -95 k/hr A cold front moves in after lunch Monday lowering freezing levels and bringing light snowfall, 5 cm or so are expected Monday night. A weak ridge builds in Tuesday AM before a more organized low moves in Tuesday afternoon into Wednesday. We can expect 15 - 20 cm before the system exits to the east Wednesday afternoon.

Avalanche Summary

Storm snow avalanche activity has greatly diminished. Continued NW winds are driving wind slab formation in exposed areas. A size 2.5 avalanche was reported from the region on a steep unsupported SE facing slope New Years Eve. While activity on the surface hoar has slowed down, I'm still very suspect of this persistent weakness at all elevation bands.

Snowpack Summary

70-100 cm of total storm snow has fallen since Christmas. Winds have redistributed the storm snow into wind slabs that are widespread in the both the alpine and treeline. Wind slabs can also be found in wind exposed areas below treeline. The mid December surface hoar/facet/crust interface is buried anywhere from 80-100cm deep. While avalanche activity on this layer has slowed, it remains a concern as incremental loading gradually adds more weight to this weak layer. Test profiles continue to show easy shears on this layer. Obvious signs of instability (whoomphing, shooting cracks, etc.) are lessening. However, slopes that have not avalanched in the last week are of particular concern for this persistent weakness. The lower snowpack is generally strong and well settled.

Problems

Wind Slabs

An icon showing Wind Slabs
Big winds combined with plenty of snow available for transportation have resulted in widespread wind slabs on lee slopes. I'd be suspect of any open slope, even below treeline.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Persistent Slabs

An icon showing Persistent Slabs
Surface hoar buried about a meter below the surface has created a dangerous and tricky avalanche problem. Activity has slowed in the Caribou's, but this layer needs to be treated with great caution. Conservative terrain choices are appropriate.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

4 - 7

Valid until: Jan 2nd, 2012 8:00AM