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Avalanche Forecast

Archived

Apr 18th, 2019–Apr 19th, 2019

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

Regions

Kootenay Boundary.

Forecast rain to mountain-tops will rapidly destabilize the upper snowpack and initiate a loose wet avalanche cycle.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

THURSDAY NIGHT: Rain to near 2500 m; 5-10 mm / Strong, southwesterly winds / Alpine low 6 C / Freezing level 2700 m.

FRIDAY: Rain to near 2300 m; 5-10 mm / Strong, southwesterly winds / Alpine high 6 C / Freezing level 2500 m.

SATURDAY: Sunny / Light, northwesterly winds / Alpine high 5 C / Freezing level 2200 m.

SUNDAY: Sunny / Light, northwesterly winds / Alpine high 8 C / Freezing level 2500 m.

Avalanche Summary

No new avalanches were reported in this region on Wednesday. However, avalanche activity is expected to increase on Friday with the forecast rain to mountain-tops.

On Tuesday, a party skiing near Kootenay Pass reported "whumphing" on solar aspects near ridgetops and triggered a size 2 storm slab avalanche sitting on a crust on a north aspect at around 2000 m. See the MIN report HERE.

On Sunday, a skier triggered a small size 1 wind slab that then stepped-down and triggered a size 2.5 persistent slab avalanche on a northwest aspect in the alpine. See the MIN report HERE.

Snowpack Summary

Rain to mountain-tops Thursday night will rapidly warm the snow and initiate a loose wet avalanche cycle at treeline and above. 20-40 cm recent snow sitting on a crust on all aspects below 2000 m which has recently been reactive to riders.

Below treeline snow is disappearing rapidly.

Problems

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.

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.