Avalanche Forecast

Issued: Jan 7th, 2015 7:40AM

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

Peter, Avalanche Canada

South Rockies.

Mild temperatures and sunny periods could make avalanche problems more prone to triggering. Stay tuned to signs of instability like recent avalanches or critical warming.

Summary

Confidence

Fair

Weather Forecast

Synopsis: We could see cloud and flurries early on Thursday before a ridge of high pressure builds in and results in clearing skies. The freezing level remains near valley bottom with slightly cooler temperatures and winds should be light. Expect a mix of sun and cloud on Friday and theres a chance we could see a thin above freezing layer (AFL) near mountaintop. Saturday looks like a mixed bag with cloud, sunny breaks, and a chance of flurries. The freezing level is at valley bottom and the AFL should disappear.

Avalanche Summary

On Tuesday, there was one report of a size 2.5 natural slab avalanche from Allison Peak in the Crowsnest Pass. A couple observers also reported easily skier or sled triggered avalanches up to size 1.5 involving the recent storm snow (average 20 cm deep).

Snowpack Summary

Up to 20 cm of recent snowfall has been shifted into wind slabs in upper elevation terrain by moderate to strong westerly winds. These new accumulations overlie hard wind slabs in exposed terrain, and low density faceted snow in sheltered areas. Up to 75 cm below the surface you will likely find a hard, thick crust which formed mid-December. This crust has overlying facets and surface hoar (up to 10 mm in sheltered locations at treeline and below). This layer seems variably reactive throughout the region. In areas where the overlying slab is thick and cohesive, large avalanches are possible at this interface. A crust/facet combo which formed in November seems to have gone dormant for the time being.

Problems

Wind Slabs

Moderate to strong winds may have created fresh and potentially reactive wind slabs in exposed lee terrain. Watch for triggering in the lee of ridge crests and terrain breaks.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

A crust which was buried in December should remain on your radar as it has the potential to produce large avalanches. Dig down and test weak layers before committing to a line.

Stick to well supported terrain and be aware of what is above you at all times.>Avoid convexities or areas with a thin or variable snowpack where triggering could be more likely.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 8th, 2015 2:00PM