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Avalanche Forecast

Archived

Jan 26th, 2020–Jan 27th, 2020

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

Regions

Kootenay Boundary.

Ongoing flurries and wind continue to build and develop slabs, watch for reactive pockets around steep rolls and ridge features.

Confidence

Moderate - The number, quality, or consistency of field observations is good, and supports our confidence.

Weather Forecast

SUNDAY NIGHT: Isolated flurries. Alpine temperature -6 C. Southwest wind 20-30 km/hr. Freezing level 1000 m.

MONDAY: Flurries, 5-10 cm. Alpine temperature -4 C. Southwest wind 20-35 km/hr. Freezing level 1300 m.

TUESDAY: Flurries and snow, 10-15 cm. Alpine temperature -3 C. Southwest wind 20-40 km/hr. Freezing level 1400 m.

WEDNESDAY: Isolated flurries. Alpine temperature -6 C. Southwest wind 20-40 km/hr. Freezing level 1000 m.

Avalanche Summary

On Saturday, natural storm slab avalanches to size 2 were reported with most occurring on north to east aspects at 1900 m and above. Skiers were able to trigger smaller (size 1-1.5) avalanches in wind loaded areas and around ridgelines and found loose dry avalanches and sloughing in steep terrain.

On Friday, storm slab avalanches up to size 2 were triggered by explosives, skiers, and failed naturally. On Thursday, skiers triggered size 1-2 storm slab avalanches including this MIN report of a skier triggered avalanche at Kootenay Pass. This avalanche was triggered on a south aspect at treeline and ran for a long distance above the recently buried crust. Several loose wet avalanches were reported on southerly aspects below 2000 m.

No persistent slab avalanches have been observed since January 14, suggesting deep weak layers have become difficult to trigger under the current conditions.

Snowpack Summary

20-40 cm of recent snow has consolidated into a slab above 1500 m. Within this recent snow are up to 3 crusts from warm temperatures and rain events during the storm. A surface crust has formed on all aspects below 1500 m and easterly aspects up to 2000 m. Additional flurries are dusting the crust at lower elevations and adding to the stubborn slab at higher elevations.

We have been tracking two layers over the past month: a layer of surface hoar buried 80-120 cm below the surface and faceted crystals and crusts near the bottom of the snowpack in certain parts of the region (especially western areas such as the Rossland Range and Boundary region). Both of these layers have shown signs of being less reactive over the past 14 days.

Terrain and Travel

  • Watch for fresh storm slabs building throughout the day.
  • Be careful as you transition into wind affected terrain.
  • Approach lee and cross-loaded slopes with caution.
  • Be alert to conditions that change with elevation.

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.