Avalanche Forecast

Issued: Jan 29th, 2018 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

Avalanche control on the Sunshine Road on Tuesday, no climbing or skiing in the slide paths tomorrow. Strong wind and snowfall overnight Monday will start a major avalanche cycle on Tuesday. Avoid avalanche terrain.

Summary

Weather Forecast

Warm temps, substantial snowfall and strong SW wind are forecasted Monday night and through Tuesday. This will initiate a major avalanche cycle. A slight cooling trend and easing snowfall is expected Wednesday.

Snowpack Summary

Recent storms have deposited 35-65cm of storm snow in the last 5 days. Increasing wind and steady snowfall today are loading 3 persistent weak layers of surface hoar and facets in the upper half of the snowpack: Jan 16 down 25-45cm; Jan 6 down 35-55cm; and Dec15 down 45-80cm. In snowpits, these layers are giving sudden test results.

Avalanche Summary

A skier remote avalanche (size 2) was reported in the Sunshine backcountry. Although visibility was limited there have been many reports throughout the forecast region of audible avalanches through the day as the storm intensifies.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Tuesday

Problems

Persistent Slabs

There are three weak layers in the upper snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on your aspect and elevation. Avalanches are occurring on these layers and human triggering is likely.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Use conservative route selection, choose supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 3

Wind Slabs

Recent winds and new snow have formed slabs in leeward areas of alpine and treeline terrain, and caused natural avalanches and small cornice failures. The slabs will be building Monday night and if triggered, may step down to persistent layers.

Use caution in lee areas. Recent wind loading have created wind slabs.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Valid until: Jan 30th, 2018 4:00PM