Avalanche Forecast

Issued: Dec 24th, 2014 7:50AM

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

ghelgeson, Avalanche Canada

Kootenay Boundary.

Riding conditions are amazing, but the snowpack is spooky. Don't let your lust for great turns lure you out of simple terrain.

Summary

Confidence

Fair

Weather Forecast

Synopsis: The Pacific storm cycle has come to a close, a dirty ridge builds in its wake allowing freezing levels to drop back to valley bottom. Look for cooler temps and mid-level cloud through the holiday weekend.Thursday: Freezing Level: Valley Bottom; Precipitation: Nil; Wind: Treeline: Light, NW | Ridgetop: Light, NWFriday: Freezing Level: Valley Bottom; Precipitation: Nil; Treeline: Light, NW | Ridgetop: Moderate, NWSaturday: Freezing Level: Valley Bottom; Precipitation: 0-2mm | 0-5cm; Wind: Treeline: Light, W/SW | Ridgetop: Moderate, NW

Avalanche Summary

Avalanche activity slowed way down Tuesday, but I suspect the storm snow from Tuesday night may produce another limited natural cycle. On Monday, a skier-triggered an avalanche remotely from 10 m away on an east aspect at 2050 m, while avalanche control produced avalanches up to size 2.5 on the recent rain crust. On Sunday just after the storm widespread natural and remotely triggered storm slab avalanches ran to size 2.5. They occurred on a variety of aspects and elevations between 1700 and 2200 m. The recently buried crust/surface hoar interface was the culprit in most of these avalanches, although in one event near Rossland, a remotely triggered storm slab in motion stepped down to the November crust/facet interface near the ground on a planar slope at 2100m.

Snowpack Summary

30 - 70cm of recent storm snow overlies a prominent surface hoar layer above a thick rain crust that extends as high as 2400 m. This crust/surface hoar interface was very reactive during the storm over the weekend, and still has the potential to produce further avalanches with additional load from new snow or wind, or in response to human triggers. High elevation north aspect slopes do not have the rain crust, but are still reported to have buried touchy surface hoar. On these slopes, deeper facets or buried surface hoar from earlier in the month may also be lurking. At the base of the snowpack, a crust/facet combo has become less likely to trigger, although a recent avalanche that occurred on this layer near Rossland indicates this layer should remain on our radar on steep, smooth terrain at treeline and in the alpine.

Problems

Storm Slabs

All the new storm snow rests precariously on a potent combination of weak surface hoar and stout rain crust. Conditions are prime for large human triggered avalanches failing 30 - 70 cm deep.

Stick to simple terrain and be aware of what is above you at all times.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Deep Persistent Slabs

An avalanche on Sunday stepped down to deeply buried weak layers which formed in November. These destructive layers should remain on our radar as they could be triggered with large inputs such as a cornice fall or an avalanche in motion.

Caution around convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 25th, 2014 2:00PM