Avalanche Forecast

Issued: Jan 16th, 2012 9:34AM

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

pgoddard, Avalanche Canada

South Rockies.

Locally heavy snowfall is possible, which could bump the danger to considerable at treeline on Tuesday in specific areas. Wednesday and Thursday's forecast is highly uncertain. Check in daily for updates.

Summary

Confidence

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

Weather Forecast

Tuesday: 5-10cm snow. Strong to gale south-westerly winds. Freezing level at valley floor.Wednesday/Thursday: Weather models show very different outcomes. Anything's possible - from dry conditions to moderate (locally heavy) snowfall, with strong westerly winds and a slight rise in temperature. Confidence is poor. Check in tomorrow for an update.

Avalanche Summary

We haven't had any reports of new avalanche activity.

Snowpack Summary

Up to 30cm recent snow fell with little wind. This overlies older wind slabs, which appear to be well bonded. New wind slabs are likely to form quickly at the first sign of wind, as plenty of loose snow is available for transport.Besides new storm/wind-related concerns, the layer we're still watching in the region is a surface hoar layer buried in early December. It's down about 85cm in the Flathead and exhibits hard, sudden planar/full propagation results, meaning that's it's stubborn to trigger but could create a large avalanche if triggered.At the bottom of the snowpack a variable facet/crust/facet sandwich is located with depth hoar up to size 5mm below the crust, and facets size 2mm above. There has been little in the way of recent activity on basal layers.

Problems

Loose Dry

Loose dry new snow will sluff easily in steep terrain. It could knock you off your feet or carry you into a terrain trap.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

New wind slabs are likely to form quickly as the the wind picks up again, due to the amount of available loose snow.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

A buried surface hoar layer in the top metre of the snowpack continues to be a concern. Although it has become stubborn to trigger, the consequences are high. It's most likely to be triggered from shallow rocky areas on a slope.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 6

Valid until: Jan 17th, 2012 8:00AM