Avalanche Forecast

Archived

Dec 25th, 2012–Dec 26th, 2012

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, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Purcells.

Confidence

Fair - Timing of incoming weather is uncertain on Friday

Weather Forecast

Wednesday: Isolated flurries with generally overcast skies, winds light to moderate from the southwest and alpine temperatures near -11.Thursday and Friday: A weak ridge of high pressure will give generally dry conditions, winds light from the west and alpine temperatures near -12.

Avalanche Summary

Recent reports indicate both natural and skier triggered avalanches to size 1.5 in wind loaded features.

Snowpack Summary

A wind event from last week formed relatively deep wind slabs in the alpine. New snow combined with wind has formed fresh wind slabs on the surface. The mid-pack is reported to be settling well. Recent reports indicate late November surface hoar (near the middle of the snowpack) and early November crust (near the base of the snowpack) have been inactive as of late. It's important to note that professionals are still cautious about these lingering persistent slab problems, but the likelihood of triggering is low. Be wary of steep complex terrain with a shallow snowpack, where triggering a persistent weakness is more likely.

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.