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Avalanche Forecast

Archived

Feb 24th, 2014–Feb 25th, 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 and human triggered avalanches likely.
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 possible, human triggered probable.

Regions

South Coast.

Don't let blue skies and fresh snow lure you into big terrain! A buried persistent weak layer is still lurking and could wake up with forecast sunshine and rapidly rising temperatures.

Confidence

Fair

Weather Forecast

Synopsis: A building upper ridge of high pressure will result in drier conditions and more sunshine for the next several days. Temperatures will also increase dramatically by Tuesday. Tuesday: A mix of sun and cloud. The freezing level is around 1200 m. Winds are light and variable. Wednesday: A mix of sun and cloud. An above freezing layer is possible between 1500 and 2300 m. Winds are light and variable.Thursday: Cloudy with sunny breaks and a chance of light precipitation. The freezing level is near 1800 m.

Avalanche Summary

There was one new report of a remotely triggered thin wind slab from a SW aspect at treeline on Saturday. A couple natural avalanches were also observed in the Steep Creek area off the Duffey Lake road on Friday. One of these appeared to release on relatively low angle terrain (30 degrees) and propagated very far. These likely released on the mid February persistent weakness. Check out Wayne Flann's Avalanche blog for photos.

Snowpack Summary

10-30 cm of cold low density new snow has fallen in the past couple days, accompanied by light to moderate W-NW winds. Older dense wind slabs may be lightly buried on a variety of aspects and in cross-loaded terrain features. In the southern portion of the region up to 200 cm of settled storm snow sits on a crust/facet combination buried in mid February. In northern sections this weakness includes surface hoar and is generally down 60-100 cm. Recent snowpack tests indicate that this weak layer may be gaining strength, but professionals remain suspect. The mid and lower snowpack are generally strong and well-settled. However, basal facets and depth hoar are likely to exist in the north of the region and still deserve respect on thin rocky alpine slopes.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

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.