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Avalanche Forecast

Archived

Dec 27th, 2011–Dec 28th, 2011

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Rockies.

There are limited field observations from this region. If you have information feel free to email forecaster.ca

Confidence

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

Weather Forecast

Tuesday Overnight: snow amounts up to 15cms. Ridgetop winds up to 100km/hr from the West. Freezing levels at valley bottom. Wednesday: Snow amounts up to 10cms. Ridgetop winds 70-110km/hr from the West, wind warning in effect. Freezing levels could rise to 1600m. Thursday: Snow amounts 5-10cms. Ridgetop winds 55-90km/hr from the West. Freezing levels near 900m. Friday: Snow amounts up to 5cms. Winds still westerly in the moderate ranges. Freezing levels at valley bottom.For more information on zonal weather patterns and timing please visit our new Forecasters Blog Post.

Avalanche Summary

No new avalanches. Nearby (in the Lizard Range) there were 2 incidents reported on December 22 and 1 on December 23. For more information please visit avalanche.ca, click Bulletins then incident report database.

Snowpack Summary

Strong westerly winds continue, creating wind slabs on lee locations and scouring on windward locations in the alpine and open treeline. A buried layer of surface hoar lies approximately 20 cm below the snow surface. This layer is not widespread and reports indicate this layer was blown and destroyed in the alpine, and wind exposed areas at treeline and below. This layer is likely found in isolated, sheltered locations at and below treeline. A well settled mid pack bridges over the basal weaknesses at the ground.

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.