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Avalanche Forecast

Archived

Mar 9th, 2015–Mar 10th, 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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Watch for wet surface snow on steep solar slopes that could lead to small loose wet avalanches. Also, watch for potentially weakening cornices with daytime warming and sunshine.

Detailed Forecast

Tuesday should be another warm and at least initially sunny day. Most areas do not have sufficient loose surface snow to become wet and easily available for wet snow avalanches. However, in isolated areas the best window for small wet loose avalanches on steeper solar slopes should occur in the late morning or mid-day before increasing high clouds and SW winds diminish the already small likelihood. 

Cornices are not listed as an expected problem, but may begin to weaken during the warmest part of the day. It's the time of year to be extra aware of the hazards cornices pose travelling along or below ridgelines. 

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

As the last snowfall occurred near the end of February; the central and southeast Cascades received the most snow with 7 inches at Mission Ridge, and generally 2 or 3 inches for the northeast Cascades. This was followed by locally strong north to northeast winds that built shallow wind slab on a variety of aspects. Sunny and gradually warmer weather has been seen the first third of March helping to stabilize local wind slab from the end of February and further consolidate the snowpack.

NWAC pro-oberserver Tom Curtis was at Jove Peak last Wednesday in the central east zone and found a strong well drained snowpack. A pit had 55 cm of strong, well bonded snow over the old mid-January facet/crust layers over rounding grains. There was about 120 cm total snow at his location at 5500 ft on a SE aspect. 

The North Cascade Heli and Mountain Guides in the Washington Pass area over the weekend reported some cool snow on north to east slopes with numerous tests giving no results.  Many slopes above treeline were quite wind and sun-affected, producing variable skiing conditions but no stability concerns. The snow study plot on a north aspect at 6600 ft above Varden Creek measured a snow depth of nearly two and a half meters! 

Here is a photo showing some varied surface snow conditions from near Silver Star Peak Friday by NWAC forecaster Dennis D'Amico.

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.