Avalanche Forecast
Issued: Jan 16th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
Recent wind slabs exist on a wide range of aspects at higher elevations. Choose terrain with the expectation that a smaller wind slab could trigger a deeper weak layer in the snowpack.
Summary
Confidence
Weather Forecast
Thursday night: Cloudy with easing flurries bringing 5-10 cm of new snow. Light to moderate southwest winds easing and shifting west.
Friday: Broken cloud cover. Light to moderate west or southwest winds. Alpine temperatures around -12.
Saturday: Cloudy with scattered flurries bringing about 5 cm of new snow. Light to moderate south winds. Alpine high temperatures around -7.
Sunday: Cloudy with isolated flurries and a trace of new snow. Light to moderate southwest winds. Alpine high temperatures around -3.
Avalanche Summary
No new persistent slab avalanches were observed on Tuesday or Wednesday, but this region has been a hot spot for recent persistent slab avalanche activity. A number of large natural avalanches up to size 3 were reported on east, southeast and south facing slopes above 2000 m in the Rossland area Monday with crowns up to 100-150 cm in depth.
In the rest of the region both natural and explosive controlled avalanches up to size 2.5 were observed on all aspects above 1800 m. Many avalanches failed on the December 27th Surface Hoar and one avalanche on a north/northeast facing slope at 1800 m involved the mid November facets.
On Sunday the bulk of the avalanche activity was limited to loose dry avalanches but a spooky avalanche was remote triggered by a group of skiers, more details and photos in this MIN report.
Snowpack Summary
Stormy weather over the past several days brought 35 to 65 cm of snow to the region. Each snowfall and interval in between has been characterized by variable wind ranging from moderate to strong and shifting from south to north and back again.
As a result, higher elevations have formed a variable array of old and new, fresh and buried wind slabs across all aspects while sheltered lower elevations have seen mainly increasing depths of low density snow.
As new snow continues to accumulate, concern is increasing for weak layers of surface hoar found around 70 to 130 cm deep. These layers have been active as recently as Monday and may reach a more widespread tipping point, even though they are gradually gaining strength. These layers are especially concerning in steep, large terrain features and shallow rocky areas.
The base of the snowpack is also weak in parts of the region where it consists of sugary faceted snow around a melt-freeze crust.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
A steady supply of new snow and variable winds have formed wind slabs on a wide range of aspects at higher elevations. Our most recent winds have been from the south, meaning north aspects may hold the newest, touchiest slabs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Several persistent weak layers are buried in the snowpack. It is possible for humans to trigger them, or for storm or wind slab avalanches to step down to them and form very large avalanches. Recent avalanche observations on deeply buried weak layers are on an increasing trend in our region.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 17th, 2020 5:00PM
