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Avalanche Forecast

Archived

Dec 10th, 2013–Dec 11th, 2013

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

South Rockies.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The region will see light snowfall amounts, gradual warming and strong ridgetop winds as the warm front of the pacific frontal system arrives on Wednesday. A series of disturbances will continue through the forecast period with the timing and intensity tricky to predict. Wednesday: Cloudy. Snow amounts 5-10 cm. Alpine temperatures near -11. Ridgetop winds moderate from the SW. Thursday: Cloudy with flurries near 3-5 cm. Alpine temperatures near -9. Ridgetop winds moderate, gusting strong from the SW.Friday: Cloudy with some sunny periods. Snow mounts near 5 cm. Alpine temperatures -6. Ridgetop winds light from the SW.

Avalanche Summary

On Monday a size 1.5 rider triggered wind slab avalanche was reported. It was easily triggered and It failed on a NE aspect around 2200 m.

Snowpack Summary

Widespread surface hoar and surface faceting continue to develop. Snowpack depths at treeline seem to vary from 50 - 110 cm. Widespread wind effect is noticeable in the alpine and at treeline.Down 30-40 cm sits a surface hoar/ facet/ crust interface. Snowpack testing showed easy results and some whumphing (failure of a weak layer below your feet). If you're seeing or feeling this, consider it a direct indicator of a buried weakness below.Near the base of the snowpack, weak sugary facets exist. This layer may be stubborn to trigger, especially in deeper snowpack areas. In shallower locations the likelihood may increase especially on a steep, convex slope. In some areas its still below threshold below treeline, and early season hazards like open creeks, and stumps exist.

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.

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.