Avalanche Forecast

Archived

Apr 8th, 2014–Apr 9th, 2014

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Little Yoho.

The biggest question is the amount of heat input that the snowpack will receive over the next few days. It is generally a good habit to start your day a bit earlier this time of year so you can be back in town by early afternoon.

Weather Forecast

The temperature is supposed to drop over the next few days (-4@ 1500m). Strong wind and very little precip (amounting to no more than 7cm over the next 3 days) will keep the danger ratings where they presently are until Friday.

Snowpack Summary

Moist snow to 2000m on all aspects and to ridge top on solar aspects. Thin wind slabs in open areas. Western areas such as Emerald and Field have a deep and stable snowpack. The Lake Louise, Hwy 93 N, & Sunshine areas have a weaker snowpack and we are still getting easy to moderate sudden collapse results on the basal depth hoar in some areas.

Avalanche Summary

Cascade Waterfall and Rogans gulley both produced avalanches size three this afternoon. Also, we have a reliable report that many avalanches occurred on Mt. Rundle between Banff and Canmore. All of these slides were due to rapid warming in the afternoon. Additionally, a small wet slide came down to the ditch on the Field Back Road.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Friday

Problems

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.

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.

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.