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Avalanche Forecast

Archived

Feb 17th, 2022–Feb 18th, 2022

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.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Inland.

New snow and wind are forming fresh slabs over a slippery crust. Avoid freshly wind loaded terrain features and watch for signs of instability like cracking or recent avalanches.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Thursday night: Flurries around 5 cm, strong northwest wind, freezing level 1200 m.

Friday: Flurries 5-10 cm, strong southwest wind, high of +1, freezing level 1200 m.

Saturday: Flurries 5-10 cm overnight then easing, moderate west wind, high of -2, freezing level 800 m.

Sunday: A mix of sun and cloud, light northwest wind, high of -4, freezing level valley bottom.

Avalanche Summary

Several skier triggered size 1 wind slabs were reported on Tuesday and Wednesday. The size and distribution of the slabs are expected to increase as snow accumulates.

Snowpack Summary

Incremental inputs of new snow are being loaded into leeward terrain features by strong wind. These fresh wind slabs sit over a thick rain crust. The 10-20 cm thick rain crust makes human triggering of avalanches on weak layers deeper in the snowpack very unlikely.

Cornices overhead are a primary concern during sunny, warm, or windy conditions. Cornice failures can trigger very large persistent slab avalanches that would otherwise be difficult to human trigger.

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.
  • Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.

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.