Avalanche Forecast

Archived

Dec 1st, 2014–Dec 2nd, 2014

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky.

Changing wind directions may have developed windslabs or an icy crust on any aspect. Windslabs may slide easily where they are sitting on a hard crust.

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

Mostly clear overnight with moderate Northwest winds and alpine temperatures around -12. Clear on Tuesday with light Northeast winds and alpine temperatures rising to about -5. There is a chance of a temperature inversion on Wednesday that might leave some near freezing air trapped in the alpine with clear skies and light winds.

Avalanche Summary

No new avalanches reported.

Snowpack Summary

Surface hoar and near surface facets are reported to be growing during the cold and clear weather. Strong Northeast outflow winds developed windslabs 10-40 cm deep since Friday, and then strong and variable winds have since loaded and reverse loaded the light dry snow that came at the end of the storm. Below this new snow is a solid weight bearing crust in all but the highest alpine slopes. There is a chance that a consolidated slab exists in some areas in the alpine above a deeply buried crust from earlier in November.

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.