Avalanche Forecast

Issued: Dec 23rd, 2018 4:00PM

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

Avalanche Canada mconlan, Avalanche Canada

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The weekend's storm has created new slabs at higher elevations that may need a bit of time to bond. Be particularly cautious in terrain features around ridges.

Summary

Confidence

High.

Weather Forecast

SUNDAY NIGHT: Mostly cloudy, freezing level 1000 m. MONDAY: Clearing over the day, light northwest winds, alpine temperature -8°c, freezing level 800 m. TUESDAY: A mix of sun and cloud, light northwest winds, alpine temperature -9°c, freezing level 500 m. WEDNESDAY: Mostly cloudy, light southwest winds, alpine temperature -9°c, freezing level 400 m.

Avalanche Summary

No new avalanches were observed on Saturday. It is likely that the snow from the recent storm was reactive to human traffic on Sunday.

Snowpack Summary

Around 30 to 40 cm of snow fell during Saturday night and Sunday's storm. The snow fell with southwest winds, likely forming wind slabs in lee terrain features. Below around 1800 m, the snow fell onto a melt-freeze crust formed by rain from Thursday's storm. It may take a bit of time for the new snow to bond to underlying surfaces. A weak layer of facets and surface hoar lies below storm snow, generally around 150 to 200 cm deep. There hasn't been reports of avalanches on this layer for over a week. That being said, this layer may still exist in isolated areas around treeline in some portions of the region. At the base of the snowpack, weak and sugary facets are found below an early-season melt-freeze crust. This weak layer has been the culprit for sporadic, very large avalanches in alpine terrain in the past few weeks. The avalanches have occurred in areas where the ground roughness is very smooth, for example glaciers, firn, and shale/rock slab slopes. An avalanche could be triggered in this layer with a very large trigger, such as a cornice fall.

Problems

Wind Slabs

An icon showing Wind Slabs
The weekend's storm produced new slabs, with the thickest and touchiest likely found in lee terrain features. It is possible that slabs could step down to deeper layers and produce larger avalanches.
Watch for signs of instability such as whumpfing, cracking, or recent avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.Cornices are large and looming near ridges. Give them a wide berth.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 24th, 2018 2:00PM

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