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Avalanche Forecast

Archived

Feb 15th, 2020–Feb 16th, 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.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Kootenay Boundary.

Potentially thick slabs can be found in wind exposed terrain, especially immediately lee of ridge crest. Caution is needed in the trees right now too, the most recent storm snow may be resting on a spotty layer of surface hoar.

Confidence

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

We’re moving into a dryer period that is expected to be with us for the foreseeable future. Freezing levels look very reasonable for the middle of February and there is a fair amount of sun in the forecast for the work week.

SATURDAY NIGHT: Freezing level around near valley bottom, moderate west/northwest wind, 1 to 5 cm of snow expected with the highest terrain potentially receiving as much as 12 cm.

SUNDAY: Broken cloud cover, freezing level around 1300 m, light to moderate west/southwest wind, trace of snow possible.

MONDAY: Scattered cloud cover, freezing level around 1000 m, light to moderate northwest wind, no significant precipitation expected.

TUESDAY: Scattered cloud at dawn, clearing by sunset, freezing level rising to about 1000 m, light north/northwest wind, no significant precipitation expected.

Avalanche Summary

On Friday wind slab avalanches were sensitive to human triggering and explosive control work to size 1.5 on lee aspects above 1900 m.

Explosive work Wednesday produced size 1.5-2 wind slab and cornice avalanches. Several small (size 1) natural and skier-triggered wind slab avalanches have been reported on east/northeast aspects in the alpine over the past few days. At least one of these occurred near treeline and was reported to have slid on a crust buried around 20 cm below the surface.

Snowpack Summary

The weekend storm produced 10 to 20 cm of new snow which is expected to further wind slab development in lee features at alpine and upper treeline elevations. The new snow is failing of a variety of surfaces: hard wind slabs around ridgetops and northerly alpine features, soft slabs and 10-15 cm of lower density snow in sheltered terrain, a thin sun crust on solar aspects, and scoured features in exposed terrain. Spotty surface hoar has also been reported under the storm snow.

A thick rain crust to mountain top sits below 25-45 cm of recent storm snow in the east of the region and 40-100 cm in the west. Recent avalanches slid on the crust or released within the storm snow. However, recent information indicates the bond at the crust is improving. Weak facet/crust layers near the base of the snowpack have not been an active avalanche problem recently. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

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.