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Avalanche Forecast

Archived

Dec 4th, 2017–Dec 5th, 2017

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

Regions

Purcells.

Fresh wind slabs are likely at higher elevations. Evaluate the snow and terrain carefully as there is still limited information from this region.

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

TUESDAY: Alpine sun and valley cloud, light wind, alpine temperatures around -7 C.WEDNESDAY: Sunny with valley cloud, light wind, inversion forming with alpine temperatures possibly reaching above 0 C.THURSDAY: Sunny with valley cloud, light wind, inversion with freezing level up to 3000 m.

Avalanche Summary

A Mountain Information Network (MIN) report from the Golden area describes multiple size 1 wind slabs produced by ski cutting on Sunday. Several size 1 wind slabs were also triggered by explosives near ridge crests throughout the region over the weekend.

Snowpack Summary

Snow from last week's storms is settling and getting redistributed into fresh wind slabs by northwest winds. Roughly 20-40 cm of recent snow sits above various crusts from the warm weather in late November. Two deeper layers may be found in the snowpack, including the November 10 surface hoar and the Halloween crust (80 to 100 cm deep). The late November crust is the most likely of these layers to develop into a problem in the future. Snow depths decrease rapidly below treeline, where the primary hazards are rocks, stumps, and open creeks.

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.