Avalanche Forecast
Issued: Mar 6th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
Settling storm snow is still sensitive to human triggers. Expect greater reactivity in freshly wind loaded features around rigelines.
Persistent weak layers continue to be reactive at treeline in the Southern Selkirks. Other areas are rated as moderate.
Summary
Confidence
Weather Forecast
A cold front approaches from the north overnight, bringing light snowfall and cold temperatures.
SUNDAY NIGHT: Increasing cloud with strong west/northwest winds. Freezing levels drop to valley bottom overnight.
MONDAY: Cloudy with isolated flurries bringing up to 5 cm of snow to the northeast corner of the region. Winds ease to moderate from the northwest. Freezing levels rise to 1500 m, alpine high of-2.
TUESDAY: A mix of sun and cloud with isolated flurries. Light northeast winds. Freezing levels at valley bottom. Alpine high of -5.
WEDNESDAY: Mostly clear with light northerly winds. Freezing levels at valley bottom. Alpine high of -10.
Avalanche Summary
Storm slab activity continues to taper off, with recent reports indicating the impact of the spring sun on the snowpack.
On Saturday, reactivity in the storm snow was limited to wind loaded areas and convex rolls, producing slab avalanches to size 2. Loose wet activity to size 2 was reported out of many steep sun affected terrain features.
Over the past two weeks we have seen the buried weak layers of surface hoar and crust from mid February and mid January regularly produce large persistent slab avalanches. Activity has been concentrated in the Valhalla, Goat, and Kokanee Ranges typically on north through southeast facing slopes at treeline elevations.
- Multiple size 2-3 avalanches were remotely triggered from ridgeline features on Friday and Saturday, up to 90cm deep.
- A natural size 2 was triggered by solar input in the Valhallas on Friday.
- On Friday snowmobile triggered size 2 occurred near Slocan. Read the MIN report here for full details.
- Operators in the Valhallas have noted whumpfing in treeline and low alpine features. This is a clear sign of instability and to consider conservative terrain choices.
Snowpack Summary
Northwest winds will redistribute recent storm snow onto south and east facing slopes. Wind loaded pockets will build over a sun crust on south-facing slopes. A layer of surface hoar may be buried in wind-sheltered terrain features over 30-50cm of settling snow.
Lower elevations have seen warm temperatures last week and have a melt freeze crust on the surface (below 1800 m).
The late February weak layer combination of crust, facets and surface hoar is buried up to 50cm deep, and has been reactive mostly on south facing slopes during periods of sun. There is some uncertainty about whether this interface will be reactive as temperatures drop.
Buried weak layers sit 50-100 cm deep, from mid February and mid January. They both consist of surface hoar and/or melt-freeze crusts. Recent trends indicate these layers have been more reactive in southern Selkirks around the Valhalla, Kokanee, and Goat Ranges. Several natural and human triggered avalanches have been produced on these layers in the last 3 days. See the Avalanche Summary for full details.
Terrain and Travel
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
Problems
Storm Slabs
30-50 cm of recent storm snow may continue to be reactive to human triggers in specific terrain features. This includes steep sun-exposed slopes, wind loaded slopes, and open convexities at treeline where there could be buried sun crusts or surface hoar layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Persistent weak layers of surface hoar and/or crust can be found 40 to 100 cm deep.
The problem is most likely found in the southern part of the Selkirks (e.g. Valhalla, Goat and Kokanee ranges), especially on open convex slopes at treeline elevations.
This problem exists on all aspects, however increased reactivity has been noted on northeast through southeast facing slopes.
Watch for signs of instability like whumpfs, shooting cracks and recent avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 7th, 2022 4:00PM
