Avalanche Forecast

Issued: Dec 5th, 2016 4:17PM

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

Avalanche Canada shorton, Avalanche Canada

Storm slabs from the recent snowfall may be reactive to human-triggering. Avoid recently wind loaded areas and be prepared to back off to mellow terrain.

Summary

Confidence

-

Weather Forecast

TUESDAY: Sunny, light northwest winds, alpine temperatures at -14.WEDNESDAY: Sunny, light north winds, alpine temperatures at -14.THURSDAY: Flurries with accumulations of 5 cm, 40-60 km/h southwest winds, alpine temperatures at -12.

Avalanche Summary

Storm slab avalanches were reported in the Duffey area on the weekend. These include a natural size 1.5 avalanche in the lee of a ridgetop, and a skier cut size 2 avalanche running on buried surface hoar on a steep northwest slope at 1760 m (see MIN report from Cerise Creek). Observations from other parts of the region are limited. Storm slabs will remain touchy on wind loaded features at higher elevations or where they exist over preserved surface hoar.

Snowpack Summary

New snow from the weekend is settling throughout the region, as 70 cm of new snow fell in the Coquihalla area, 30 cm around Manning Park, and 20 cm in the Duffey area. Snowpack tests on Sunday suggest the new snow was poorly bonded with the old snow. Overall, the storm snow is likely more reactive than in the neighboring Sea to Sky region. Several surface hoar layers have been reported in the northern part of the region, including a 30 cm deep layer with 1-2 mm decomposing surface hoar at treeline in the Duffey area, and a 60 cm deep layer with 3-5 mm surface hoar in the Pemberton area. Information on the distribution and reactivity of these layers is limited. A widespread crust can be found 70-100 cm deep throughout the region. Although this layer has been generally unreactive throughout all of the Coast Mountains, it may be possible to trigger this layer in shallow wind-affected starts zones, as recent observations in Manning Park found a mix of surface hoar and facets above the crust were reactive to snowpack tests.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm slabs are most likely on wind-loaded features and in parts of the region that received the heaviest snowfall over the weekend. In the Duffey area, storm slabs sit above buried surface hoar and have the potential for wide propagations.
Avoid steep, open slopes.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 6th, 2016 2:00PM

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