Avalanche Forecast
Issued: Mar 9th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
TRettie,
Avalanche Canada
Use extra caution around ridge crests and steep roll overs where triggering avalanches is most likely.
Summary
Confidence
Weather Forecast
Wednesday night: no new snow expected. Light northwest winds and a low of -19 at 1600m.
Thursday: A mix of sun and cloud. Light to moderate west wind. High of -7 at 1600m.
Friday: Overnight flurries bringing a trace of snow then clearing to a mix of sun and cloud. Moderate west wind. High of -2 at 1600m.
Saturday: stormy with 10 to 15cm of snow expected and moderate to strong southwest winds. Freezing levels rising to 1600m.
Avalanche Summary
On Tuesday a group of skiers remotely triggered a slab avalanche on an east aspect near ridgetop. We suspect it failed on the facets above the late February layer. Wind loading above this layer was a factor.
On Monday, ski cuts produced size 1 wind slab and loose dry avalanches. Explosive control work on steep shady treeline features produced no results.
Over the weekend near Fernie, storm slabs were reactive to explosives size 2-3 on northeast aspects in the alpine and upper treeline. We received several reports of rider triggered size 1 storm slabs in the alpine and loose dry avalanches up to size 1.5 around treeline.
Snowpack Summary
5-10 cm of lightly wind affected recent snow sits over a sun/temperature crust on solar aspects and below 1800 m.
A rain crust buried somewhere in the 50-100 cm of last week's storm snow has been found as high as 2100 m and is well bonded to surrounding snow. At up to 10 cm thick, it effectively bridges any deeper instabilities in the snowpack.
In areas and elevations where the rain crust is thinner, we continue to monitor a potentially weak interface 50-100 cm deep. It consists of sun and freezing rain crusts as well as weak faceted crystals on shaded aspects.
Although we haven't seen recent activity on a couple of weak layers buried in January, they still appear in snowpack models and local operators continue to track them. These consist of a layer of surface hoar and a crust buried more than 1m deep in most places.
The lower snowpack is generally well consolidated, with a crust/facet layer from early December found near the ground. It is currently considered dormant but could become active later this season.
Terrain and Travel
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
Problems
Wind Slabs
The most likely places to trigger a wind slab include unsupported convex roll-overs and where recent snow sits over a crust.
Aspects: East, South East, South, South West, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 10th, 2022 4:00PM
