Avalanche Forecast

Issued: Nov 26th, 2017 5:02PM

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

Avalanche Canada cgarritty, Avalanche Canada

Avalanche danger is steadily increasing as snowfall and wind continue to load the snowpack. Each pulse of new snow and wind brings it closer to the tipping point.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Monday: Periods of snow bringing 15-25 cm of new snow, increasing overnight. Strong to extreme southwest winds. Freezing level to 1000 metres with alpine temperatures of around -3.Tuesday: Periods of snow bringing 15-20 cm of new snow. Strong southwest winds. Freezing level to about 800 metres with alpine temperatures around -5.Wednesday: Heavy snowfall bringing 20-30 cm of new snow. Strong to extreme southwest winds. Freezing level to 1300 metres with alpine temperatures around -2.

Avalanche Summary

No recent avalanches have been reported. Looking forward, high winds and snowfall rates are set to rapidly load the snowpack and establish very dangerous avalanche conditions for the next few days. Any travel in avalanche terrain will require very conservative routefinding and travel practices. Please post your observations to the Mountain Information Network (MIN)

Snowpack Summary

Snowpack depths at treeline elevations average about 90-150 cm in the south of the region. Here, an elevation dependant 30-50 cm of new snow from recent and ongoing stormy weather now forms the upper snowpack. Variable winds over the course of this stormy period have progressively encouraged slab formation in the new snow, especially at higher elevations. A thick rain crust that formed early last week exists below the new snow and has produced a wide range of results (from easy to hard) in snowpack tests. Below this crust, two weak layers are noted to have formed during the early season. (October 31 and November 11). The deeper late October layer has produced moderate to hard sudden collapse results in snowpack tests. Beneath it, the bottom 20 cm of the snowpack features loose, sugary crystals that have begun to show signs of improved bonding. Looking further to the north of the region near Ningunsaw, recent reports describe a starkly different snowpack. Here, a possible 10-30 cm of recent storm snow may now overlie a thin lower snowpack composed mainly of weak, sugary snow. Snow depths in this part of the region are only beginning to approach threshold depths for avalanching.

Problems

Storm Slabs

An icon showing Storm Slabs
Touchy new storm slabs are building up at all elevations. Slab size and reactivity will increase with each new pulse of snowfall and wind. Storm slab releases may have potential to step down to a deeper weak layer to produce a very large avalanche.
If triggered, storm slabs may step down to deeper layers resulting in large avalanches.The new snow will require several days to settle and stabilize.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 3

Valid until: Nov 27th, 2017 2:00PM

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