Avalanche Forecast

Issued: Jan 25th, 2018 5:12PM

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

jsmith, Avalanche Canada

Kootenay Boundary.

Potential for human triggering of large avalanches remains high. Now is the time to remain disciplined and stick to a conservative approach towards terrain.

Summary

Confidence

Moderate - Timing of incoming weather systems is uncertain on Sunday

Weather Forecast

FRIDAY: Mostly cloudy with isolated flurries / Light southwesterly ridgetop winds / Alpine high of -8.SATURDAY: Cloudy with flurries; 5-10 cm of new snow / Moderate southwesterly ridgetop winds / Alpine high of -5.SUNDAY: 10-25cm of new snow / Moderate to strong southwesterly ridgetop winds / Freezing level rapidly rising to around 1500m.

Avalanche Summary

Over a dozen natural and human triggered size 2 storm slab avalanches were reported on all aspects and elevations throughout this region on Wednesday. The new snow was described as "becoming electric with wide propagations and running far and fast". These storm slabs and the persistent slabs beneath them are expected to remain reactive to human triggers.

Snowpack Summary

The snowpack in this region is currently being described as "Complex" and "Spooky".20-30cm of new snow brings recent storm snow total to approximately 55-70 cm which has been redistributed by strong southerly winds. Currently, the primary layer of concern was buried in mid-January and is down around 60-90cm. It is composed of a mixture of surface hoar (weak, feathery crystals) and/or a crust. This layer has been reactive to snowpack tests on all aspects and elevations.Below this layer lies a second crust/surface hoar interface buried early-January that is now 100-120 cm below the surface. The mid-December surface hoar layer is buried 120-150 cm below the surface. This layer still produces "sudden" test results and 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, and may co-exist with facets.

Problems

Storm Slabs

20-30cm of new snow and wind continue to create touchy storm slabs reactive to human triggers. If triggered, these slabs have the potential to step down to deeper weak layers buried in the snowpack.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use small slopes with low or no consequence to test the bond of the new snow.Be cautious when transitioning into wind effected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

The snowpack is complex and has produced very large avalanches on up to four separate weak layers buried 60 to 140cm below the surface. A conservative approach and moderate-angled, simple terrain are good ways to manage a complex snowpack.

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.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Jan 26th, 2018 2:00PM