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Avalanche Forecast

Archived

Apr 15th, 2014–Apr 16th, 2014

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

Regions

Purcells.

Avalanche danger can rise very quickly with warming and solar radiation. Be aware of changing conditions and overhead hazards.For more insight into spring danger ratings, check out our latest Blog Post.

Confidence

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

Weather Forecast

Wednesday: Mix of sun and cloud. Winds light and variable. Freezing level  1800m.Thursday: Light to locally moderate snowfall possible.  Winds moderate southwest. Freezing level 2300mFriday: Cloudy with sunny periods and scattered flurries. Light west winds. Freezing level 1900m

Avalanche Summary

Reports from the past 2 days include:-A natural size 3 cornice triggered avalanche was reported running in the alpine on a north aspect in the central part of the region. The resulting avalanche ran on a steep rocky slope and had a fracture line 3m deep. -Another cornice triggered avalanche was reported from the northern part of the region. This was a size 3 on a southeast aspect in the the alpine. The fracture line was 100cm deep running on a suspected crust.

Snowpack Summary

Mainly sunny weather and the freezing level reaching up to 2100m has created moist snow and/or a supportive crust on all aspects and elevations except for high elevation north-facing terrain. Three persistent weak layers exist in the highly variable snowpack of the Purcells:-The mid-March sun crust/surface hoar layer down 50-80cm seems to be laying dormant for the time being. -The early-March crust/facet/surface hoar layer down around 80-120cm has become less susceptible to human triggering, but still has the capacity to produce large avalanches.-The mid-February crust/facet/surface hoar combo is typically down 60 - 120cm. Direct triggering of this layer has become unlikely, however, cornice fall, a smaller avalanche in motion or prolonged warming may wake this layer up, which would result in very large and destructive avalanches.-Weak basal facets exist in many areas, but triggering is unlikely.

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.