Avalanche Forecast

Issued: Jan 6th, 2019 4:03PM

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

Avalanche Canada ghelgeson, Avalanche Canada

The storm snow is settling out nicely below treeline, but there's been a ton of wind over the last 72 hours and we have limited alpine observations. Factor the potential for large human triggered avalanches at above treeline into your travel plans.

Summary

Confidence

High -

Weather Forecast

Someone or something is playing with the storm switch, flipping it back and forth. Storm on, storm off, storm on. We get a brief respite Monday which may even offer a bit of sun. Another storm approaches the coast moving through the interior on Tuesday/Wednesday.SUNDAY NIGHT: Freezing level at valley bottom, light southwesterly breeze at most elevations with strong west wind at ridgetop, 1 to 5 cm of snow possible.MONDAY: Broken cloud cover, clearing through the day, freezing level at valley bottom, light southwest wind at most elevations, moderate west wind at ridgetop, a few centimeters of snow  possible.TUESDAY: Clear skies at dawn with cloud cover steadily increasing through the day, freezing level at valley bottom, light variable wind, no significant precipitation expected, trace of snow possible Tuesday night.WEDNESDAY: Overcast, freezing level at valley bottom, light variable wind at most elevations with moderate southwest wind at ridgetop, 1 to 5 cm of snow possible.

Avalanche Summary

On Thursday and Friday a widespread natural avalanche cycle produced avalanches that averaged size 2, but storm slab avalanches as large as size 3.5 were reported from steep alpine features. A few different cornice failure events also produced very large avalanches. 

Snowpack Summary

Thursday and Friday's storm produced 40 to 80 cm of new snow accompanied by moderate to strong wind generally out of the south. Wind effect is widespread in the alpine as well as isolated features at treeline. A 1 to 2 mm "zipper" (melt/freeze/mist) crust under the new snow has been reported in the mountains surrounding Revelstoke. Below this the snowpack is generally strong and well settled. At the bottom of the snowpack is a crust that formed in late October which is considered dormant at this time.

Problems

Storm Slabs

An icon showing Storm Slabs
Wind effect is widespread in the alpine and wind has made it's way into isolated features at treeline too. Potentially deep wind and storm slabs may remain sensitive to human triggering. Slopes immediately lee of ridgecrest are the most suspect.
Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.Back off if you encounter whumpfing, hollow sounds, or shooting cracks.Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 2.5

Valid until: Jan 7th, 2019 2:00PM

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