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Avalanche Forecast

Archived

Mar 4th, 2015–Mar 5th, 2015

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

Light winds and mid or high clouds should be seen on Thursday. The most clouds will be seen over the Olympics and north Cascades.

It is hard to say how much of a problem loose wet avalanches might be on Thursday. Watch for wet snow deeper than a few inches or rollerballs or pinwheels on steep solar slopes. The problem of loose wet avalanches should not be extensive but limit your terrain choices if you see more activity than expected.

Small areas or pockets of wind transported snow from last Friday and Saturday is most likely to linger on unusual south to northwest facing slopes on Thursday. But on most slopes the sunny weather will have caused these layers to bond and merge with underlying layers and it should no longer be a problem.

Cornices will not be listed as a problem yet but start to practice checking the ridges for these as we shift into spring.

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 in the Cascades was late last week when up to about 7 inches of snow fell east of the crest.

This was followed by local strong northeast winds in the Cascades Friday and Saturday. This is expected to have caused the most transport near treeline onto lee west slopes.

Minor cooler weather on Sunday and Monday has been followed by sunny and gradually weather on Tuesday and Wednesday. This should have have mostly stabilized the recent wind slab layers.

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

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.

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.