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Avalanche Forecast

Archived

Apr 16th, 2016–Apr 17th, 2016

Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.

Regions

Banff Yoho Kootenay.

Watch for a weak freeze Sunday morningĀ  to prime conditions for poor travel and likely an avalanche cycle Sunday through Tuesday as a ridge brings warm air and sunny skies.

Weather Forecast

A weak freeze is expected Sunday morning as warm air invades from the south through the day. Watch for SIGNIFICANT HEATING as calm winds and clear skies allow strong solar effect combined with freezing levels in excess of 3500m. With no freeze expected Monday or Tuesday expect the heating effects to compound each day as freezing levels reach 3800m.

Snowpack Summary

5 to 10cm recent snow sits on a well established melt-freeze crust on all aspects. This surface snow became moist today with solar heating slopes. N aspects in the high alpine above 2600m remain more winter like having yet to receive a significant warm up. In many places the upper snowpack sits on a weaker deep persistent layer of rounding facets.

Avalanche Summary

Loose wet activity to sz 2 on steep solar slopes with the surface snow failing over the melt-freeze crusts.

Confidence

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

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.