Avalanche Forecast

Issued: Dec 25th, 2016 3:55PM

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

Avalanche Canada shorton, Avalanche Canada

Strong winds will maintain dangerous avalanche conditions at higher elevations.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

MONDAY: Isolated flurries with trace accumulations, 30-50 km/h southwest winds increasing throughout the day to 50-70 km/h in the evening, alpine temperatures -10C.TUESDAY: Flurries with accumulations up to 10 cm, 50 km/h southwest winds, alpine temperatures -5C.WEDNESDAY: Isolated flurries with trace accumulations, 50 km/h west winds, alpine temperatures -8C.

Avalanche Summary

The most recent low density snow produced several natural and explosive triggered size 1.5-2 avalanches over the weekend. Last week, explosive triggers released several larger avalanches (up to size 2.5) running on weak sugary facets between 40 and 100 cm deep.Wind slabs remain the primary concern for human-triggering, as they sit above weak sliding layers and will continue to build as winds pick up throughout Monday. Persistent slabs releasing on weak layers that formed in early December are also becoming a concern. The recent explosive results suggest these layers could potentially wake up with extra loading from new snow or wind, or possibly be triggered in shallow snowpack areas.

Snowpack Summary

Recent flurries delivered 15-30 cm of low density powder, which now sits above hard wind slabs and settled storm snow from last week. A variable interface that formed during the mid-December cold snap can be found 50-80 cm deep. This interface consists of hard wind packed snow in exposed terrain, weak faceted (sugary) snow, and surface hoar up to 20 mm in sheltered areas. This interface could evolve into a persistent slab problem once the storm snow settles into a slab. Deeper in the snowpack you may find another layer of surface hoar in sheltered areas or weak facets that were buried in early December. The thick crust from mid-November is near the bottom of the snowpack and reports suggest that the crust is currently well bonded to the surrounding snow.

Problems

Wind Slabs

An icon showing Wind Slabs
Expect fresh wind slabs to form as winds pick up and redistribute loose snow. If triggered, wind slabs could potentially step down to deeper weak layers.
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 26th, 2016 2:00PM

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