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Avalanche Forecast

Archived

Apr 6th, 2014–Apr 7th, 2014

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

Regions

South Coast.

What's going to happen to the snowpack if it warms up significantly on Monday/Tuesday? Read a discussion here...

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

By Tuesday the cold front will reach the south coast bringing light-moderate precipitation, cloudy skies and rising freezing levels. Precipitation will be less on the Duffy.Monday: A mix of rain and snow up to 10 mm. Freezing levels rising to 2300 m. Alpine temperatures near 5.0 degrees. Ridgetop winds moderate from the SW, gusting strong. Freezing levels will slowly start to drop overnight to 1800 m. Tuesday: Periods of rain 15-25 mm. Alpine temperatures near 5.0 and freezing levels rising to 2100 m with no re-freeze overnight. Ridgetop winds remain strong from the SW.Wednesday: A mix of sun and cloud. Light precipitation. Alpine temperatures near -3.0 and freezing levels dropping to 1200 m. Ridgetop winds moderate from the SW.

Avalanche Summary

Small loose dry avalanches were seen from steep rocky terrain features. Loose wet avalanches were also seen on solar aspects. I suspect natural activity will continue with the warmer temperatures and rain through Monday/Tuesday. Smaller surface avalanches may trigger deeper weak layers, especially in thinner snowpack areas.

Snowpack Summary

Up to 20 cm of new snow sits above a mix of surface hoar, facets and melt freeze crusts. The new snow seems to have a poor bond to old surfaces and isolated wind slabs likely exist. Warmer temperatures and rising freezing levels will likely weaken the snow surfaces and become moist or wet.Recent warm temperatures have helped to settle and strengthen the upper snowpack and snowpack tests have been producing hard resistant planar shears on the late March crust down 30-50 cm.The persistent weak layers from early March and early February continue to be a concern. The March melt-freeze crust/surface hoar is reported to be down 60 - 100cm. The February crust/facet/surface hoar layer is now deeply buried down 150 - 250cm. These layers are mostly inactive at this time, but could re-awaken with extended warming, solar influence and precipitation through the forecast period.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.