Avalanche Forecast

Issued: Feb 14th, 2019 5:49PM

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

shorton, Avalanche Canada

Kootenay Boundary.

Another storm is on the way and maintaining dangerous avalanche conditions. With two buried surface hoar layers in play, the trees are not the safe haven they normally are. It's time to stick to simple, well-supported terrain.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

THURSDAY NIGHT: 5-15 cm of snow, moderate to strong southeast wind, alpine temperatures drop to -10 C.FRIDAY: Cloudy with scattered flurries and localized accumulations of 5 cm during the day, moderate southwest wind, alpine high temperatures around -6 C, snow picks up in intensity Friday evening bringing another 5-15 cm.SATURDAY: Scattered flurries easing off throughout the day with localized accumulations of 5-10 cm, light wind, alpine high temperatures around -8 C.SUNDAY: Mostly cloudy with clear breaks later in the day, light wind, alpine high temperatures around -12 C.

Avalanche Summary

On Thursday, fresh wind slabs were very reactive to human triggering on all aspects. Two large (size 2) skier-triggered slab avalanches were reported at treeline elevations with crowns up to 80 cm thick. Numerous smaller (size 1) skier-triggered wind slabs were also reported, including some triggered from a distance (remotely).On Wednesday, numerous size 1-2 storm slabs were reactive to human and explosive triggers.On Tuesday, natural and human triggered storm slab avalanches were widespread to size 2 on all aspects/elevations. The storm slabs were very touchy, and some were remote triggered from as far as 50 m away.

Snowpack Summary

Storm slabs will continue to grow thicker and touchier with the incoming storm. 25 to 40 cm of snow from earlier this week has been blown around by strong wind and formed very touchy wind slabs. This snow sits on a variety of old surfaces that include a sun crust on southerly aspects, variable wind affected snow, and weak feathery surface hoar crystals at and below treeline. The snowpack now hosts two buried surface hoar layers. The February 1st surface hoar is down 40 to 60 cm and has been recently reactive to human triggers. The mid-January surface hoar is 60 to 100 cm below the surface. This deeper layer of surface hoar is most prevalent below treeline on shady aspects, but it does not seem to be a widespread problem in the region. Below that, the snowpack is well settled.

Problems

Storm Slabs

Storm slabs have been a problem all week and will grow thicker and touchier with another 10-25 cm possible on Friday. The problem is further complicated by buried surface hoar in the trees.

Choose simple, low-angle, well-supported terrain without convexities.Back off if you encounter whumpfing, hollow sounds, shooting cracks or recent avalanches.Keep your guard up, storms slabs have been recently reactive at ALL elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

Two buried surface hoar layers are in the upper meter of the snowpack; one is down 40 to 60 cm and has been recently active, the other is down 60 to 80 cm. These layers are at a time of enhanced sensitivity as they adjust to the new load.

Surface hoar distribution is highly variable. Avoid generalizing your observations.Caution around sheltered open areas at treeline and below including cutblocks, gulleys, and glades.If triggered, storm slabs in-motion may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Feb 15th, 2019 2:00PM