Avalanche Forecast

Issued: Jan 27th, 2017 4:29PM

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

shorton, Avalanche Canada

Kootenay Boundary.

Warm windy weather this weekend could make persistent slabs touchy in thin snowpack areas.

Summary

Confidence

High - Due to the number and quality of field observations

Weather Forecast

SATURDAY: Cloudy, moderate west winds, a weak inversion keeping alpine temperatures around 0 C. with sunny periods.SUNDAY: Cloudy, strong west winds, possible temperature inversion bringing alpine temperatures around +1 C.MONDAY: Cloudy, moderate northwest winds, freezing level dropping with alpine temperatures around -5 C.

Avalanche Summary

No recent avalanches have been reported. Warmer alpine temperatures over the weekend may make the persistent slabs more touchy in thin snowpack areas. Although persistent slabs were inactive this past week, they produced large avalanches last weekend in the Bonnington and Rossland ranges and deserve careful consideration what selecting terrain. Strong winds may also form fresh wind slabs in exposed areas.

Snowpack Summary

A variety of surface conditions exist including pockets of light snow, sun crusts, shallowly buried surface hoar, and wind affected snow. A total of 30-50 cm of settled storm snow now sits above a weak interface that was buried in mid-January. The interface is composed of weak facets, surface hoar ,and/or sun crusts. The strength of this interface has generally improved, but has still given some easy to moderate sudden results in recent snowpack tests. Areas with thin snowpacks (less than 150 cm) have a weak snowpack structure with sugary facets near the ground. This includes shallow alpine slopes and most of the Rossland range.

Problems

Persistent Slabs

Several persistent weak layers are buried 50-150 cm deep and have proven reactive to human triggering. Conservative terrain use is essential in managing the problem, especially in thin snowpack areas.

Carefully evaluate terrain features by digging and testing on adjacent, safe slopes. Be aware of the potential for large avalanches due to deeply buried weak layers.Carefully evaluate and use caution around thin snowpack areas.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Wind Slabs

Watch for pockets of wind slabs on exposed features near ridge crests and cross-loaded gullies. Remember a small avalanche may provide enough force to trigger a deeper weak layer.

Be cautious as you transition into wind affected terrain.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Jan 28th, 2017 2:00PM