Avalanche Forecast

Issued: Jan 31st, 2018 3:33PM

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

Avalanche Canada jlammers, Avalanche Canada

Deeply buried weak layers exist throughout the region and a cautious approach remains critical. Don't let the lure of powder pull you into bigger terrain.

Summary

Confidence

High -

Weather Forecast

Thursday: 5-15cm of new snow / Moderate southwest winds / Freezing level at 1000mFriday: 2-4cm of new snow / Light southwest winds / Freezing level at 500mSaturday: Light flurries / Light and variable winds / Freezing level at 1500m

Avalanche Summary

Reports from Tuesday reflect increased visibility over terrain that was obscured during Monday's storm. Evidence of a natural avalanche cycle involving each of our persistent weak layers was observed, with numerous avalanches reaching Size 3.5 and several crown fractures up to 3 metres deep. These are believed to be some of the deepest crowns in the region's historical record. Here's a great MIN post from Kootenay Pass that details some of the recent activity.Looking forward, expect newly formed wind slabs and the persistent slabs beneath them to remain reactive to human triggers with the potential for very large and destructive avalanches.

Snowpack Summary

Recent storms have brought around 100 cm of snow to the region over the last couple of weeks. On Monday the recent precipitation fell as rain below about 1300 metres. Where it fell as snow, strong southwest winds have again redistributed it into touchy wind slabs.Aside from wind slab instabilities at the surface, the primary layer of concern from mid-January is buried beneath all the storm snow at 80-110cm deep. It is composed of a mixture of weak surface hoar and/or a crust. Numerous recent natural avalanches to size 2.5 have been reported on this sensitive layer and human triggering large, destructive avalanches on this layer remains likely.Below this layer lies a second crust/surface hoar interface buried early-January that is now 110-130 cm deep. Several recent avalanches have stepped down to this layer.The mid-December surface hoar layer is buried 120-150 cm below the surface. This layer has continued to produce step down releases and "sudden" test results. It is most pronounced at treeline, but is also present below treeline . Two laminated crusts created by rain events in late November lay just below the mid-December interface.

Problems

Persistent Slabs

An icon showing Persistent Slabs
The snowpack is complex and continues to produce very large avalanches on several weak layers buried 80 to 150 cm below the surface. Moderate-angled, simple terrain selection remains critical to safe mountain travel.
Be aware of the potential for large avalanches due to the presence of buried surface hoar.Be mindful that deep instabilities are still present and have produced recent large avalanches.Good day to make conservative terrain choices.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3.5

Wind Slabs

An icon showing Wind Slabs
New snow and wind on Wednesday night are expected to form new wind slabs in higher elevation lee terrain. A surface avalanche in motion could be what it takes to trigger a deeper and more destructive persistent slab avalanche.
If triggered, wind slabs may step down to deeper layers and result in large avalanches.Be cautious as you transition into wind affected terrain.Avoid lee and cross-loaded terrain near ridge crests.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 1st, 2018 2:00PM