Avalanche Forecast

Issued: Feb 2nd, 2018 6:14PM

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

Avalanche Canada shorton, Avalanche Canada

Stormy weather will elevate the danger this weekend. Minimize your exposure to avalanche terrain when there's rapid loading from new snow and wind.

Summary

Confidence

Moderate - Timing of incoming weather systems is uncertain

Weather Forecast

SATURDAY: 10-20 cm Friday night then clearing and cooling throughout the day, strong northwest wind, freezing level dropping back to valley bottom.SUNDAY: The next system arrives Sunday morning delivering 10 cm snow throughout the day and continuing into the evening with another 15-30 cm Sunday night, moderate west wind, alpine high temperatures around -8 C.MONDAY: Clearing throughout the day with isolated flurries, light to moderate southwest wind, alpine high temperatures around -5 C.

Avalanche Summary

Natural avalanche activity was observed on Friday morning, producing several 30 cm thick slabs in the latest snow.A few persistent slab avalanches released on Wednesday, most likely failing on the mid-January crust. This includes a natural size 3 avalanche on a southwest slope at 1150 m near Exstew, a few skier triggered slabs (size 1-2) in thinner snowpack areas (east of Terrace and the northern part of the region). The mid-January layer was also active in the Shames area last Saturday, where a skier triggered a size 2 avalanche on a northeast alpine slope. In this case, the weak layer was composed of surface hoar. Overall, activity on persistent weak layers has been limited recently, but enough to suggest these layers may remain reactive through this current storm.

Snowpack Summary

Fresh snow will continue to accumulate the next few days. In some areas up to a metre of storm snow has already accumulated over the past week. Warm temperatures are promoting the settlement of new snow, while westerly winds are blowing snow around in exposed areas.A weak layer buried in mid-January remains a concern and is now 60-100 cm deep. In most areas this layer is a crust, but it may also be surface hoar in sheltered areas at treeline and below. This layer produced a few human triggered avalanches throughout the region over the past week, and may remain reactive as it adjusts to the weight of the new snow.In thinner snowpack areas (north and inland), deeper crust / surface hoar layers that were buried in December and early January may still be a concern. They are buried over 100 cm below the surface, but may be triggerable from thin spots.

Problems

Storm Slabs

An icon showing Storm Slabs
Fresh storm slabs are building and will be very touchy at higher elevations and in wind-affected terrain.
Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Minimize exposure during periods of heavy loading from new snow and wind.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
A weak layer buried 60-100 cm below the surface has potential for human triggering. Storm slab avalanches may also step down to this layer.
Avoid areas with overhead hazard.Caution around convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Feb 3rd, 2018 2:00PM

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