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Avalanche Forecast

Archived

Mar 2nd, 2015–Mar 3rd, 2015

Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

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It is getting to be the time of year when you often need to watch for both winter and spring types of avalanche conditions. It is always good to read the forecast for details.

Detailed Forecast

A period of northeast ridge top winds and east pass winds should be seen in the Cascades this afternoon and tonight.

Then decreasing winds and sunny weather should be seen in the Cascades on Tuesday.

Watch for new shallow wind transported snow on unusual south to west facing slopes on Tuesday. Older wind slab from February 27th-28th is also most likely to linger on similar slopes.

The sun will be out and stronger and the days are getting longer so keep an eye on solar slopes for wet snow and signs of loose wet snow on solar slopes on Tuesday.

Due to the low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation. Many areas below treeline do not have enough snow (new or existing) to pose an avalanche hazard. 

Snowpack Discussion

The North Cascades Mountain Guides in the Washington Pass area reported a well bonded dense snowpack on February 22nd. No results from tests and rounding grains were seen at the January 15th facet/crust layers.

NWAC pro-observer Tom Curtis was in the north end of the Chiwakums on February 25th and found minor new snow on a hard thick crust, no avalanche problems and a low avalanche danger in all the elevation bands.

The latest snowfall was February 25-27th when up to about 7 inches of snow fell east of the crest.

This was followed by local strong northeast winds in the Cascades February 27-28th. This is expected to have caused the most transport near treeline onto lee west slopes.

A minor weak weather system yesterday and today did not cause significant precipitation or change in snow conditions.

The persistent weak January 15th facet/crust layers can still be identified in parts of the NE Cascades but have been stabilizing and have become unlikely to trigger. As a result the Persistent Slab problem has been removed from the northeast zone.

Problems

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.