Avalanche Forecast

Issued: Jan 8th, 2018 4:05PM

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

Avalanche Canada pgoddard, Avalanche Canada

Lots of uncertainty in the snowfall forecast for Tuesday and Wednesday. If it's dumping snow, consider the avalanche danger high.

Summary

Confidence

Low - Forecast snowfall amounts are uncertain

Weather Forecast

TUESDAY: Cloudy with snow. Snowfall amounts are hard to call. One senior meteorologist is predicting a 'Fernie effect', which could bring up to 40 cm of dry snow to parts of the South Rockies in short order late in the day. Light to moderate winds. Alpine temperature near -6.WEDNESDAY: Moderate westerly winds. Light snow. Alpine temperature near -15.THURSDAY: Moderate to strong winds. Light snow. Alpine temperature near -15.

Avalanche Summary

A timber sledder triggered and was caught in a small avalanche on a road cut on Sunday. It occurred a little below treeline, south of the Crowsnest. Avalanche conditions seem especially touchy in this type of terrain right now. Give extra thought to the presence of terrain traps like roads, gullies and trees. Even a small avalanche can have increased consequences in combination with a terrain trap.Reports over the last few days have been limited, but recent whumpfing and a bunch of  persistent slabs last week are all evidence of this problem. With warming or increased load by snow and/or wind-loading, persistent slab activity is likely to increase again.

Snowpack Summary

The snowpack is variable across the region, but the two key concerns are touchy persistent slabs and wind slabs. Wind slabs may exist lower on the slope than normal, due to recent extreme south-west winds. In some parts of the region, windward alpine slopes are scoured; and variable wind slabs are found at treeline and alpine elevations. A touchy weak layer from mid-December (predominantly feathery surface hoar crystals and/or a sun crust) is found at treeline and below. Slabs are failing very easily on this layer with the weight of a person or machine.Deeper in the snowpack, an early season rain crust and sugary facets make up the picture. Overall snowpack depths are variable across the region. It's generally shallower in the east.

Problems

Persistent Slabs

An icon showing Persistent Slabs
New snow may overload an already touchy weak layer, making avalanches especially likely in below treeline terrain.
Avoid avalanche terrain around treeline.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Wind Slabs

An icon showing Wind Slabs
Wind slabs can be found at treeline and alpine elevations. Recent extreme winds have stripped some aspects and may have left wind slabs further down slope than normal.
Back off if you encounter whumpfing, hollow sounds or shooting cracks.Use ridges or ribs to avoid areas of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 9th, 2018 2:00PM

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