Avalanche Forecast

Issued: Nov 22nd, 2015 8:34AM

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

Avalanche Canada rbuhler, Avalanche Canada

It's early in the season but there is more than enough snow for avalanches. If you are out in the mountains, please post your observations to the Mountain Information Network. Here is a great report from Saturday: http://goo.gl/XuKbn7

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

A Pacific storm system will interact with cold Arctic air on Monday resulting in snowfall throughout the region. 15-25cm are expected between midday Monday and midday Tuesday. Amounts should be greatest in the north of the region. Freezing levels are expected to be between 500 and 1000m during the storm and alpine winds are forecast to be moderate to strong from the SW at the front of the storm. By the end of Tuesday, cold Arctic air becomes the dominant feature for the foreseeable future. Sunny and cold conditions are expected for Wednesday with outflow winds.

Avalanche Summary

No recent avalanches have been reported. If you are out in the mountains, please send us your observations.

Snowpack Summary

Limited reports from the region suggest that anywhere from 100 to 150cm of snow sits on the ground. There are two crusts and one surface hoar layer in the snowpack that are of potential concern. But be aware as you read this that there is very little data on these layers and you should investigate the snowpack in your local area. The new snowfall will be sitting on a crust that is on or just below the current snow surface. This will likely be the bed surface for any wind slab or storm slab avalanches going forward. A thick crust layer and a layer of surface hoar both potentially sit in the middle of the snowpack but the stability and distribution of these layers throughout the region is not yet known. New loading could increase the reactivity of these layers or smaller avalanche may have the potential to step down. Dig down and test these layers before committing to avalanche terrain. New wind slabs in leeward features may be sensitive to human-triggering for several days. If you're out in the mountains, please send us your reports. Check out the recent conditions video from Whitewater at: https://youtu.be/lmM4gDom1wM

Problems

Wind Slabs

An icon showing Wind Slabs
New wind slabs are expected to form on a variety of aspects.  In areas that receive more than 25cm, a more widespread storm slab problem may develop.
Use caution in lee areas in the alpine. New wind loading may create wind slabs. >Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
The reactivity of a crust layer and a surface hoar layer in the middle of the snowpack is unknown and these layers should be treated with extra caution until there is more information.
Choose well supported terrain without convexities. >If you plan on increasing your exposure to avalanche terrain, do it gradually as you gather information. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Nov 23rd, 2015 2:00PM

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