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Avalanche Forecast

Archived

Feb 17th, 2024–Feb 18th, 2024

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, Dogtooth, East Purcell.

A deep persistent slab problem remains a concern where the near-surface crust is thin.

Low-probability, high-consequence problems are best managed with conservative terrain choices.

Confidence

Moderate

Avalanche Summary

On Friday and Saturday, numerous small (size 1) dry loose and wind slab avalanches were reported in steep terrain. South of Golden, one large (size 2) avalanche was reported in extreme terrain on a west aspect in the alpine.

On Thursday numerous small (size 1) skier-triggered and natural wind slabs were reported on all aspects in the alpine.

Snowpack Summary

10 to 20 cm of settling snow sits over a frozen crust that formed in early February. This crust is generally supportive to the weight of a human, but it gets thinner and less supportive in the alpine.

Consistent north winds in the alpine have been transporting available snow and building small wind slabs on lee features.

The midpack is generally faceted and the lower snowpack contains weak faceted grains, depth hoar, and crusts that continue to produce sporadic large avalanches.

Weather Summary

Saturday Night

Clear. No new snow expected. Light south or southwest ridgetop wind. Treeline temperature around -7 °C.

Sunday

Partly cloudy. No new snow expected. Light west or southwest ridgetop wind. Treeline temperature around -5 °C.

Monday

Partly cloudy. No new snow expected. Light southeast ridgetop wind. Treeline temperature around -6 °C.

Tuesday

Partly cloudy. No new snow expected. Light south ridgetop wind. Treeline temperature around -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Carefully evaluate steep lines for wind slabs.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.

Problems

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

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.