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West Slopes South - South of I-90 to Columbia River

Issued: 6:00 PM PST Friday, February 2, 2018
by Dallas Glass

NWAC avalanche forecasts apply to backcountry avalanche terrain in the Olympics, Washington Cascades and Mt Hood area. These forecasts do not apply to developed ski areas, avalanche terrain affecting highways and higher terrain on the volcanic peaks above the Cascade crest level. 

Dangerous avalanche conditions will exist throughout the area Saturday. Avoid steep open slopes at all elevations where you are likely to trigger an avalanche. Large natural Loose Wet avalanches were reported Friday indicating a dangerous and active cycle.

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Avalanche Problems for Saturday

Loose Weti

Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

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Wind Slabi

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

  • Avalanche Problemi
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Avalanche Summary:

Warm wet weather Friday created moist to wet surface snow conditions up to 6500 feet. A natural Loose Wet avalanche cycle occurred Friday with peak warming and precipitation.

Above treeline, below freezing temperatures, additional snow, and moderate winds formed new Wind Slabs on a variety of aspects. Poor visibility and stormy conditions has limited observations at higher elevations.

Cornices throughout the area have grown very large.

Observations

Stevens Pass

NWAC Avalanche Forecaster Josh Hirshberg traveled in the Stevens Pass areas Friday. Josh noted numerous natural Loose Wet avalanches on all aspects. These avalanches ranged from small to large, with some travelling 1000 vertical feet. Rain created 6” of wet surface snow by Friday afternoon.

Snoqualmie Pass

Alpental Ski Patrol Thursday reported very large cornices along ridges in the Alpental Valley.

South

An avalanche professional in the Crystal backcountry Thursday noted lingering wind slab instabilities near ridges. By late in the day light rain was already effecting the below treeline bands.

Forecast for Saturday:

Warm weather and precipitation will maintain dangerous avalanche conditions Saturday. Avalanche problems will be dependent on precipitation type.

Stay off of steep slopes with wet surface snow where you are likely to trigger Loose Wet avalanches. Natural Loose Wet avalanches were reported Friday. Many of them grew large and traveled well into runout areas. This is a clear indication that this avalanche problem is active and should be respected.

Isolated Wet Slab avalanches could occur during periods of higher intensity rain. Wet Slabs are extremely difficult to predict and assess. Avoid avalanche terrain if you see signs of slab activity occurring during the day Saturday.

Above treeline, moderate to strong winds will continue to build Wind Slabs. Use visual clues such as blowing snow, plumes, fresh cornices, and uneven snow surfaces to detect building Wind Slabs. Avoid steep slopes where snow is being deposited.

Less precipitation in some areas Saturday will limit the development of avalanche hazard.

No Corresponding Mountain Weather Forecast Available

USE AT YOUR OWN RISK

This Backcountry Avalanche Forecast is provided in conjunction with the US Forest Service, and is intended for personal and recreational purposes only. Safe backcountry travel requires preparation and planning, and this information may be used for planning purposes but does not provide all the information necessary for backcountry travel. Advanced avalanche education is strongly encouraged.

The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and the accuracy or reliability of the data provided here is not guaranteed in any way. This forecast describes general avalanche conditions and local variations will always occur. This forecast expires 24 hours after the posted time unless noted otherwise.