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Avalanche Forecast

Archived

Feb 15th, 2022–Feb 16th, 2022

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

Regions

Northwest Inland.

 

Small wind slabs in isolated locations on steep terrain may remain reactive to human triggers.

The crust formed by the rain event last week has created a significant falling hazard in steep terrain.

Confidence

High -

Weather Forecast

TUESDAY NIGHT: Increasing cloudiness / Strong, northwest wind / Low of -6 / Freezing level valley bottom.

WEDNESDAY: Cloudy with isolated flurries; 0-3 cm, and another 3-5 cm overnight / Extreme, west wind / High of -1 / Freezing level 1000 m.

THURSDAY: Cloudy with flurries; 3-5 cm / Extreme, northwest wind / High of 1 / Freezing level 1200 m.

FRIDAY: Cloudy with flurries; 5-10 cm / Strong, west wind / High of 1 / Freezing level 1200 m.

Avalanche Summary

Several natural size 2 cornice failures were reported on Monday. None of them triggered slab avalanches on the slopes below.

Snowpack Summary

5-10 cm of wind-pressed snow overlies a thick (10-15 cm) rain crust that extends to mountain tops. This crust has created challenging travel conditions and a "slide-for-life" hazard on steep slopes.

Small wind slabs may be found on lee features in the alpine. 

The weak layers in the snowpack (such as the crust or surface hoar layers down around 100 cm) are unlikely to human trigger in areas where a hard surface crust is present. If the surface crust is warmed up and breaks down, triggering persistent slab avalanches becomes more likely.

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

Terrain and Travel

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

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.