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Avalanche Forecast

Archived

Dec 15th, 2015–Dec 16th, 2015

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

Regions

Sea To Sky.

You don't have to be an avalanche expert to submit to the MIN. If you've been out in the mountains, we'd love to hear about what you've seen.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Mainly clear skies are forecast for Wednesday and Thursday morning. Increased cloud is expected throughout the day on Thursday with 10-30cm of new snow falling between Thursday afternoon and Friday morning. Ridgetop winds should be light to moderate from the north on Wednesday, switching to strong and southwesterly with Thursday's snowfall. Freezing levels should hover around 500m for the forecast period. For a more detailed weather overview, check-out our Mountain Weather Forecast at: avalanche.ca/weather

Avalanche Summary

On Monday there were a few reports of small loose wet avalanches running on steep, sun-exposed slopes. They occurred in response to solar radiation and brief warming. On Tuesday, we received reports of human-triggered wind slab activity to size 1 on exposed convex rolls at treeline and in the alpine.

Snowpack Summary

On Tuesday, 5-10cm of low-density snow was redistributed by winds into new wind slabs at treeline and in the alpine. These new wind slabs overlie 40-50cm of storm snow from last weekend. Limited observations suggest the recent storm snow has gained considerable strength, although I'd continue to be wary of lingering pockets of wind slab on high elevation, wind-loaded slopes. On steep, south-facing terrain you may find a sun crust from solar warming on Monday. Below 2200m, a hard rain crust can be found approximately 120cm below the surface.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.