Avalanche Forecast

Issued: Jan 20th, 2019 4:02PM

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

Avalanche Canada cgarritty, Avalanche Canada

It's all about the new snow right now. In the alpine, it's been blown into thick and reactive wind slabs. At mid and lower elevations, thinner but more widespread slabs have been releasing over a weak layer of surface hoar.

Summary

Confidence

High -

Weather Forecast

Sunday night: Cloudy with clear periods. Light to moderate north winds. Monday: Mainly cloudy. Light northwest winds shifting to southwest in the evening before increasing. Alpine high temperatures around -11.Tuesday: Cloudy with isolated flurries and a trace of new snow, increasing a bit overnight. Light to moderate southwest winds. Alpine high temperatures around -6.Wednesday: Mainly cloudy with continuing flurries bringing 5-10 cm of new snow, including overnight accumulations, ending early in the day. Alpine high temperatures around -5.

Avalanche Summary

Sunday was a busy day for avalanches running on the newly buried weak layer below our new snow. Numerous small storm slabs were observed releasing naturally, with remote (from a distance) triggers, and with skier traffic and ski cutting throughout the South Columbias as well as in neighbouring regions.Storm slabs were especially reactive, although usually quite thin (15-20 cm), from about 1500 to 1800 metres, where surface hoar is most prevalent. In the alpine, where surface hoar is less well preserved, quite a few larger (size 2), deeper wind slabs released with similar triggers, with a focus toward northeast aspects in the lee of recent moderate to strong winds.On Saturday, the new snow was reactive to skier traffic in steep terrain producing fast moving sluffs and some small (size 1) slab avalanches. Small natural avalanches (20 cm deep) were also reported on north and east aspects.Slab avalanches are currently most likely in wind affected terrain and at mid elevations where our surface hoar is best preserved. The key is watching for signs of the new snow becoming reactive, such as cracking, whumpfing, or stiffer deeper pockets of snow.

Snowpack Summary

15-25 cm of new snow from the weekend now sits above a layer of large surface hoar crystals and sun crusts. The new snow has been settling into a thin but reactive slab above this weak layer, with enhanced reactivity noted at elevations between about 1500-1800 metres, where surface hoar is particularly well developed. Although the surface hoar is less prevalent in the alpine, strong southerly winds during and immediately after the storm formed deeper deposits on lee slopes that have proven similarly reactive at higher elevations. New snow deposits that overlie sun crust on steep, south-facing slopes may be especially touchy. The middle and lower portions of the snowpack are generally well-settled and strong.

Problems

Storm Slabs

An icon showing Storm Slabs
15-25 cm of new snow has been blown around into reactive slabs at higher elevations. A layer of surface hoar and crusts beneath the new snow is making slabs extra touchy at middle and lower elevations.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Watch for whumpfing, hollow sounds, and shooting cracks.Use extra caution around open slopes and convex rolls

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 21st, 2019 2:00PM