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Avalanche Forecast

Archived

Apr 7th, 2014–Apr 8th, 2014

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

Regions

Sea To Sky.

Check out the new Forecaster Blog to gain insight of how to manage cornices, and how warming influences the snowpack.

Confidence

Fair - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

Precipitation and strong SW winds will prevail as the cold front moves across the region Tuesday. Tuesday: Snow amounts up to 25 cm. Freezing levels 1900 m then dropping overnight to valley bottom. Ridgetop winds moderate from the SW. Wednesday/ Thursday: Mainly cloudy with possible sunny breaks in the afternoon and some flurries expected. Ridgetop winds light from the West. Freezing levels near 1200 m.

Avalanche Summary

Numerous size 1 wind slab, loose dry and loose wet avalanches were reported on Sunday. One size 2.5 slab avalanche was also reported and the failure plane was a buried crust, no other details noted. Cornices are sagging, with one failure a couple of days ago. With new snow and strong winds forecast for Tuesday, I suspect natural avalanche activity will be on the rise.

Snowpack Summary

Higher elevation areas have recently received up to 25 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 1800 m 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. 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 re-freeze.

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.