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Avalanche Forecast

Archived

Mar 16th, 2025–Mar 17th, 2025

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford, Moyie, Kokanee, Retallack, Valhalla, Whatshan.

Sticking to simple or non-avalanche terrain is recommended while the storm snow settles and stabilizes.

Avoid overhead hazard, especially during periods of sun.

Confidence

High

Avalanche Summary

A widespread region-wide avalanche cycle of natural, human and explosive-triggered avalanches occurred during the stormy weather over the last few days. Slabs were observed at all aspects and elevation zones, and reached up to size 3 (very large). While most were storm slabs, a significant number also failed on persistent weak layers.

Snowpack Summary

40 to 60 cm of recent snow has formed widespread storm slabs that are slowly settling and stabilizing. Southwesterly winds may have built especially reactive slabs on lee north through east facing slopes near ridgetops.There is potential for the new snow to overload deeper persistent layers in the upper to mid snowpack, causing storm slabs to step down. These layers include:

  • Facets/surface hoar/crust from early March buried 40-70 cm.

  • Facets/surface hoar/crust from mid-February buried 60-100 cm

  • Facets/surface hoar/crust from late January buried 100-160 cm.

The rest of the snowpack is well settled with no other layers of concern.

Weather Summary

Sunday Night

Cloudy with 1 to 8 cm of snow. 25 to 30 km/h south ridgetop wind. Treeline temperature -8 °C.

Monday

A mix of sun and cloud. 10 to 20 km/h variable ridgetop wind. Treeline temperature -5 °C.

Tuesday

Mostly sunny. 20 to 30 km/h northwest ridgetop wind. Treeline temperature -5 °C.

Wednesday

A mix of sun and cloud. 30 to 40 km/h south ridgetop wind. Treeline temperature -3 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for human triggerable storm slabs at lower elevations, even on small features.
  • Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
  • Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.