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Avalanche Forecast

Archived

Mar 8th, 2022–Mar 9th, 2022

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

North Rockies.

Recently formed wind slabs may remain reactive to human triggers; especially where they are sitting on a slippery sun crust and/or a weak layer of surface hoar.

Cornices are very large in many areas, minimize your exposure time below them.

Confidence

High -

Weather Forecast

TUESDAY NIGHT: Clear / Light north winds / Low of -22 / Freezing level surface.

WEDNESDAY: Sunny / Moderate northwest wind / High of -9 / Freezing level surface.

THURSDAY: Increasing cloudiness with isolated flurries; 0-3 cm / Moderate northwest wind / High of -6 / Freezing level surface.

FRIDAY: Cloudy with flurries; 3-10 cm / Strong west wind / High of -1 / Freezing level rising to 1300 m.

Avalanche Summary

A skier triggered size 1.5 wind slab was reported on a east aspect below a treeline ridgetop on Monday. The wind slab was sitting on a layer of recently buried surface hoar which resulted in wide propagation of the slab.

Riders may get surprised by widely propagating wind slabs that are sitting on crusts and/or surface hoar.

Snowpack Summary

10-15 cm of recent snow and west/northwest winds have formed wind slabs on lee features at treeline and above. These slabs may remain more reactive on south facing slopes where they are sitting on a slippery sun crust. Below the recent snow, there may be a layer of small surface hoar that is likely most pronounced on northerly aspects or sheltered locations.

Lower elevations have seen warm temperatures last week and have a melt freeze crust on the surface. 

The mid and lower snowpack is generally well-settled and strong in most areas, with multiple crusts throughout. No recent persistent slab avalanches have been reported on these layers.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Use ridges or ribs to avoid areas of wind loaded snow.
  • Carefully evaluate steep lines for wind slabs.
  • Minimize your exposure time below cornices.

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.