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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

Sea To Sky.

What's going to happen to the snowpack if it warms up significantly over the next couple of days? 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.Monday: A mix of rain and snow with freezing levels rising to 2100 m. Alpine temperatures near 2.0 degrees. Ridgetop winds moderate from the SW, gusting strong. Freezing levels will slowly start to drop overnight to 1600 m. Tuesday: Periods of snow 15-25 cm. Alpine temperatures near 0.0 and freezing levels rising to 1700 m with no re-freeze overnight. Up to 20 mm expected by Tuesday. Alpine temperatures near 2.0 degrees. Ridgetop winds remain strong from the SW.Wednesday: Snow 5-10 cm. Alpine temperatures near -3.0. Ridgetop winds light from the SW.

Avalanche Summary

On Friday, a deep persistent slab avalanche occurred on a NE aspect at 2400 m. It is suspect that it failed on the mid-March interface. Additionally, numerous size 1 wind slab avalanches were easily triggered by the weight of a person on leeward loaded slopes near ridgetop. A natural cornice failure also pulled out small size 1 wind slab from the slope directly below.

Snowpack Summary

Higher elevation areas have recently received up to 20 cm of new snow which sits on a variety of old snow surfaces including surface hoar, facets and melt freeze crusts. Isolated wind slabs have formed and a poor bond seem to exist, especially on slopes with a buried crust.Recent warm temperatures have helped to settle and strengthen the upper snowpack and tests are producing hard resistant planar shears on the late March crust. Below treeline a spring-like melt-freeze snowpack exists. Persistent weak layers exist lower in the snowpack. The mid-March surface hoar/ crust interface now down 80 -110 cm and is decreasing in sensitivity to triggering. The early-March crust/facet layer is down about 100-150 cm and the early February layer is now down close to 200 cm. These layers are largely dormant at this time; however, they should remain on your radar as we begin to transition into a warm-up with minimal overnight refreeze 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.