Avalanche Forecast

Issued: Nov 27th, 2014 7:47AM

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

Avalanche Canada Peter, Avalanche Canada

Rapid cooling should help stabilize the snowpack and lower the avalanche danger heading into the weekend. However, we could see new issues arise if we see decent snowfall on Friday (mainly Cascades).

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Friday: Temperatures start to plummet early with freezing levels dropping to 500 m by mid-day. We could see a good pulse of snow (10-20 cm), mainly in the Cascades. Ridge winds ease. Saturday: Mainly sunny. The freezing level is at valley bottom. Winds are light to moderate from the NE. Sunday: Sun and cloud. The freezing level remains at valley bottom. Winds are light from the W-NW.

Avalanche Summary

A size 2 slab avalanche was observed off the east side of Joffre Peak in the Duffy Lake area on Wednesday morning. This slide triggered several loose wet sluffs lower on the slope that ran quite far. The observer also reported several older crowns from alpine terrain that probably release overnight or early that morning. Please let us know what you're seeing out there at forecaster@avalanche.ca.

Snowpack Summary

There are few actual observations from the region to start the season. This is based mostly off weather station data and the weather forecast. 40-60 cm of snow fell by early Wednesday morning but temperatures rapidly spiked resulting in rain to around 2000 m. Higher elevations may have continued to see wet snow accumulate. As temperatures start to drop on Friday we could see a dusting of fresh snow (or even 10-20 cm) on top of a new rain crust. A weak layer of facetted snow on a crust may be lurking deeper in the snowpack. However, it's possible this weakness was 'flushed' out with the recent heavy precipitation. There's limited recent info on this weakness so I recommend digging to confirm the existence of the layer, its depth, and to test its strength.

Problems

Storm Slabs

An icon showing Storm Slabs
Rapid cooling should help stabilize the snowpack but conditions may be right for localized snow storms on Friday. We could see new storm or wind slabs develop in some areas. This new snow will probably sit on a crust and may not bond well.
Choose conservative lines and watch for clues of instability.>Avoid freshly wind loaded features.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 28th, 2014 2:00PM