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Avalanche Forecast

Archived

Dec 8th, 2013–Dec 9th, 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

Poor - Due to the number of field observations

Weather Forecast

The strong arctic high will gradually start to break down. Weak frontal waves will cross the interior regions, bringing some cloud cover and light snowfall amounts. The next significant change in the pattern should develop mid-week.Monday: Mix of sun and cloud. Alpine temperatures show a high of -18. Ridgetop winds will blow moderate from the SW. Snow amounts near 5 cm.Tuesday: Cloudy. Alpine temperatures show a high of -14. Ridgetop winds will blow light from the West. Snow amounts near 5 cm.Wednesday: Mainly cloudy. Alpine temperatures show a high of -9. Ridgetop winds will blow light from the West. Snow amounts 5-10 cm.

Avalanche Summary

No reports of avalanche activity.

Snowpack Summary

Widespread surface hoar and surface facetting continues to develop. Snowpack depths at treeline seem to vary from 80 - 120 cm. Strong ridgetop winds from the N-NE has redistributed snow onto S-SW aspects, creating reverse loaded slopes. Widespread wind effect is noticeable in the alpine and at treeline, but reports suggest wind slabs are stubborn to trigger.Below the recent storm snow 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, I suspect you will find sugary weak facets. This layer may be stubborn to trigger under the current conditions, but if it was to happen, it would most likely be on a steep, convex slope with a thin snowpack

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.