Avalanche Forecast

Issued: Jan 3rd, 2019 4:57PM

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

Avalanche Canada dsaly, Avalanche Canada

Heavy snowfall and high wind are producing touchy storm slabs. Give the snowpack time to stabilize.

Summary

Confidence

Low - Intensity of incoming weather systems is uncertain

Weather Forecast

THURSDAY NIGHT: Snow, 20-30 cm. Moderate south wind with extreme gusts. Freezing level rising to 1800 m.FRIDAY: Heavy snow, 20-35 cm. Moderate to strong southwest wind with extreme gusts. Freezing level dropping to 1200 m.SATURDAY: Flurries, 8-15 cm snow. Light south wind gusting moderate. Freezing level 1100 m.SUNDAY: Flurries, 5-12 cm snow. Moderate southwest wind. Freezing level below 1000 m.

Avalanche Summary

On Thursday, storm slab avalanches to size 2 were failing with explosives and skier traffic. Through the day, rain falling to 1500 m triggered loose wet and wet slab avalanches. Prior to Wednesday, avalanche activity seems to have tapered off as temperatures cooled off over earlier in the week. On Sunday there were reports of a few explosives controlled size 1-1.5 storm and wind slabs. On Saturday reports indicated several explosives controlled size 2 storm and wind slabs in the alpine and treeline. Most of these avalanches were running on a layer of surface hoar buried around December 26.

Snowpack Summary

Heavy snowfall, rising freezing levels and extreme winds are setting up a widespread storm slab problem. Around 40-80 cm of new snow since Wednesday adds to 30-50 cm of snow from the past week. This new load potentially sits on a weak layer of feathery surface hoar at treeline elevations and on a crust below 1800 m.A weak layer of sugary facets and surface hoar lies around 150 to 200 cm deep in the snowpack. There have not 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 parts of the region. The additional weight of the new snow could stress deeper weak layers too.

Problems

Storm Slabs

An icon showing Storm Slabs
Large natural avalanches are expected with heavy deposits of new snow falling with extreme wind.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.If triggered the storm slabs may step down to deeper layers resulting in very large avalanches.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1.5 - 3.5

Valid until: Jan 4th, 2019 2:00PM

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