Avalanche Forecast
Regions: Kootenay Boundary.
Still stormy!
Heavy rain and snow overnight will continue to keep avalanche danger elevated. Even as snowfall rates taper on Tuesday, the snowpack will need time to adjust to the new load.
Travel in avalanche terrain is not recommended and stay clear of runout zones.
Confidence
High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
Monday night: Heavy precipitation continues overnight with 20-40 mm with strong southwest wind. Freezing levels rise to approximately 2000 m, treeline temps could reach +3.
Tuesday: Snowfall easing during the day, 5-15 cm possible, moderate to strong southwest wind, freezing levels hovering around 1800-2000 m, treeline highs of +3.
Tuesday night into Wednesday: Light snowfall, light to moderate southwest wind, freezing levels dropping to around 1700 m.
Thursday: Trace of new snow, wind light and variable, freezing levels between 1500-1700 m
Avalanche Summary
Several naturally triggered size 2 storm slab avalanches were reported in the region on Monday. Explosives control yielded storm slab results up to size 2.5.
On Sunday there were reports of small accidentally triggered wind slabs.
Snowpack Summary
By Tuesday morning there could be over 60 cm (depending on your location in the region) of new snow forming touchy slabs over a variety of old surfaces like old wind affected snow, sun crusts, and cold weak crystals on shaded aspects. Rain will likely soak new snow overnight on Monday night at treeline and below treeline elevations.
An interface from mid-February is also on the radar. Facets over old wind-pressed snow and sun crusts, as well as spotty surface hoar crystals have been slow to heal. This layer was previously only reactive in wind-loaded terrain where a slab had formed but may become more widespread if covered with a more cohesive slab on all aspects due to recent storm snow.
Two layers of buried surface hoar from January are likely now down over a meter deep. Most recently, this surface hoar was most reactive in sheltered areas around treeline in the east of the region and appeared to be dormant through the rest of the region. As the storm progresses and more load is added to the snowpack, this surface hoar will get tested and avalanches have the potential to step down to these deeper layers.Â
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Avalanche Problems
Storm Slabs
Continued snowfall, southwest wind and high freezing levels will keep avalanche danger high on Tuesday. Avoiding avalanche terrain and staying clear of overhead hazard is the best way to stay safe during periods of heavy snow accumulation. As the snowpack becomes saturated with rain at lower elevations, storm slabs may entrain wet loose snow and run further than expected.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely - Almost Certain
Expected Size: 1 - 3.5
Loose Wet
Loose wet avalanches will be a concern at lower elevations where rain has destabilized the snowpack causing it to lose cohesion. These avalanches can start from a point and pick up a surprising amount of mass, especially in steep terrain and gully-type features. Storm slabs may entrain wet loose snow at lower elevations and run further than expected. Steer clear of steep terrain and don't walk the dog in runout zones!
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Likely
Expected Size: 1 - 2.5
Persistent Slabs
Two buried persistent weak layers could be potential problems as the new snow accumulates.
A weak layer from mid-February is likely down over 60 cm and may become more reactive as the overlying snow forms a thicker and more cohesive slab. Two weak layers of surface hoar from January are likely down over a meter and were primarily a concern in the east of the region on northerly aspects around treeline.
Storm slab and loose wet avalanches have the potential to step down to these deeper layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 2 - 3.5