Avalanche Forecast

Issued: Dec 28th, 2014 7:51AM

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.

jlammers, Avalanche Canada

South Rockies.

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Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

A dry arctic ridge will dominate the region for the forecast period. Skies will be mainly clear with ridge top temperatures hovering at about -25, and moderate northeasterly winds.

Avalanche Summary

Wind slabs to size 2.5 were observed in high elevation terrain in the south of the region on Saturday. In one reported case, a wind slab in motion stepped down to the buried December crust.

Snowpack Summary

On the surface, up to 30cm of low-density snow exists. In the alpine and at treeline, strong to locally extreme winds have been conducive to blowing this snow into large and reactive wind slabs in exposed lee areas. 50 - 70 cm below the surface (more in wind affected areas) you may find a crust which formed in December. The crust, which may have surface hoar on top of it, may extend into the alpine to at least 2100 m. Where the crust exists, it may be bridging triggers from penetrating to deeper persistent weaknesses that formed earlier in the season. However, on high alpine slopes above where the rain crust formed, or in areas where rain didn't occur, deeply buried facets may still be susceptible to triggers.

Problems

Wind Slabs

Strong and variable winds have redistributed loose surface snow into wind slabs in lee terrain. Watch for triggering behind 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, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

A crust which formed in December should remain on your radar. Not much is known about its distribution in the South Rockies. However, in neighboring regions it has produced large avalanches. Dig down and test weak layers before committing to a line.

Make observations and assess conditions continually as you travel.>Stick to well supported terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Dec 29th, 2014 2:00PM