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Avalanche Forecast

Archived

Mar 27th, 2024–Mar 28th, 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.

Convex terrain features with a shallow or thin-to-thick snowpack at treeline and above are the most likely places to trigger persistent slab avalanches.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported on Tuesday or Wednesday by the time of publishing.

On Friday, a helicopter landing on a slope remotely triggered several large (size 2) persistent slab avalanches on a north aspect in the alpine south of Golden. The avalanches failed on the crust which was down 80 to 110 cm in that location.

Snowpack Summary

5 to 15 cm of recent snow overlies predominantly crusty surfaces, except for northerly aspects at upper elevations.

A widespread crust with sugary facets above is down 40 to 110 cm. Steep or convex terrain features with a shallow or thin to thick snowpack at treeline and above are the most likely places to trigger this layer. However, when a thick surface crust is present, human triggering this layer is unlikely.

The bottom of the snowpack is generally weak and faceted, with the potential to produce very large avalanches.

Weather Summary

Wednesday Night

Mostly cloudy with 1 to 2 cm of snow. 10 to 20 km/h south ridgetop wind. Treeline temperature -4 °C.

Thursday

Partly cloudy, clearing with up to 5 cm of snow. 15 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1700 m.

Friday

Partly cloudy with up to 5 cm of snow. 15 km/h southwest ridgetop wind.  Treeline temperature -4 °C. Freezing level 1500 m.

Saturday

Mostly clear skies with up to 5 cm of snow by morning. 15 km/h west ridgetop wind.  Treeline temperature -4 °C. Freezing level 1700 m.

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.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Conditions may have improved, but be mindful that deep instabilities are still present.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.