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Avalanche Forecast

Archived

Apr 9th, 2021–Apr 10th, 2021

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

Regions

Kootenay Boundary.

Seeking high, north-facing dry snow will put you in the same terrain as wind slabs that form Friday night. Gather good information about wind loading and reactivity of new snow before committing to your line. Steep slopes that catch sun will likely shed loose snow naturally.

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

Friday night: Cloudy with flurries bringing about 5 cm of new snow. Strong southwest winds.

Saturday: Mainly cloudy with easing flurries and another 3-5 cm of new snow. Moderate northwest winds easing over the day. Alpine high temperatures around -9 with freezing levels to 1000 metres.

Sunday: Sunny. Light southwest winds. Alpine high temperatures around -3 with freezing levels to 1700 metres.

Monday: A mix of sun and cloud. Moderate northeast winds. Alpine high temperatures around -4 with freezing levels to 1700 metres. 

Avalanche Summary

Reports from the Kootenay Pass area on Thursday describe periods of intense solar warming triggering several natural point releases entraining our recent storm snow up to size 1.5.

A similar pattern is likely to occur through the weekend as fresh accumulations are once again triggered by their first exposure to solar input. New and recent wind slabs may also be reactive to triggers in leeward terrain features, especially in areas with greater recent snowfall amounts, such as Kootenay Pass.

Snowpack Summary

Light new snow amounts over Friday night will accumulate over a new melt-freeze crust on solar aspects and otherwise add to a rapidly settling 5-20 cm of snow from Wednesday's storm. This previous storm snow formed wind slabs on north through east aspects, overlying yet another crust on all aspects below 2000 metres. Wind affected new and recent accumulations may add to settled dry snow in limited terrain above this elevation. 

Terrain and Travel

  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
  • Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.
  • Even brief periods of direct sun could produce natural avalanches.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.