Avalanche Forecast

Issued: Jan 28th, 2012 9:57AM

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

Avalanche Canada ghelgeson, Avalanche Canada

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain on Sunday

Weather Forecast

For better or worse, weather models are far from perfect. They have a particularly tough time with situations like the one we're in now. The models call for rapidly changing freezing levels, strong to extreme winds out of the SW and uncertain precip amounts. My best guess for the South Columbias is 30 cm of snow. The big winds will likely get right to work Saturday night out of the SW with sustained strong values, gusting extreme. Freezing levels will spike Sunday and may rise as high as 1800m. Cooling will build in Monday and then Tuesday looks to be fairly dry. This is all fine & good, but I must admit that my confidence in any model is quite low for the short term, so, take this weather forecast with a grain of salt and be ready for rapidly changing conditions.

Avalanche Summary

Very little significant avalanche activity was reported from the region Friday.

Snowpack Summary

60 - 100 cm of storm snow has fallen in the last week which has settled out nicely in the region. A few stubborn windslabs were observed on Friday, but these were largely unreactive to provocation.Going a little deeper in the snowpack we find that the snowfall from the past week rests on dry cold snow formed during an Arctic Outbreak. A Rutschblock test in the north showed a result of RB6, MB down 90 on this layer. In the south a CTE test produced a failure down 70 at this interface. We may see some limited activity out of this layer Sunday, but I think that will be its last kick at the can.Below this lies the January 13th SH/FC layer that is spotty in distribution, but it is still capable of performing. Deep in the pack the mid December layer has gained a lot of strength, but it may still be an issue in areas of thin shallow snowpack.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs 50 - 100 cm in depth are possible as extreme winds go to work on 30 cm of new storm snow. With this much loading I'd give wind exposed terrain a miss Sunday as it will need a day or two to adjust to the new load.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Storm Slabs

An icon showing Storm Slabs
The weekend storm is expected to bring 25 - 35 cm of snow to the region which will come in cold, go warm and then cool down again. This awkward structure lends itself to slab development. Watch for storm slabs at all elevations Sunday.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Cornices

An icon showing Cornices
Big winds have created large cornices. Give these behemoths a wide berth whether traveling near them or far below them. Failing cornices have the potential to trigger large avalanches.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

2 - 6

Valid until: Jan 29th, 2012 8:00AM