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Stevens Pass

Issued: 8:11 PM PST Saturday, February 3, 2018
by Josh Hirshberg

Dangerous avalanche conditions exist near and above treeline. Use extra caution in terrain steeper than 35 degrees and where you may be exposed to steep slopes from above. Very large and destructive wet avalanches and cornice falls are possible where heavy rain is falling on a previously dry snowpack.

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Avalanche Problems for Sunday

Wet Slabsi

Wet slabs occur when there is liquid water in the snowpack, and can release during the first few days of a warming period. Travel early in the day and avoiding avalanche paths when you see pinwheels, roller balls, loose wet avalanches, and during rain-on-snow events.

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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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Avalanche Summary:

Warm wet weather Friday and Saturday 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 drifted snow on a variety of aspects. Poor visibility and stormy conditions have limited observations at higher elevations.

Cornices throughout the area have grown very large. Glide cracks have opened up on typical rock slabs especially in the Snoqualmie Pass and Mount Baker area.

Observations

Stevens Pass

NWAC Avalanche Forecasters and observers noted numerous natural wet loose avalanches on all aspects Friday and Saturday. These avalanches ranged from small to large, with some travelling 1000 vertical feet. As of Saturday rain created over 1 foot of wet surface snow, extending below the January 29th crust.

Snoqualmie Pass

On Saturday, Alpental Ski Patrol reported audible cornices collapses along ridges in the Alpental Valley. Both patrol and an NWAC observer reported Glide avalanches, visible glide cracks, and significant amounts of water running through the snowpack. Also reported were many wet loose avalanches at all aspects near and below treeeline

South

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

Forecast for Sunday:

Expect dangerous and complex avalanche conditions today due to heavy rain and warming temperatures. Wet avalanches can be very large and can pose serious consequences. Avalanches big enough to bury a car are not out of the question today. The most dangerous slopes are near and above treeline. Previously dry snow above treeline will become saturated with water for the first time. Avoid slopes with a wet snowpack that are 35 degrees and steeper.

Wet Slab avalanches hold today’s gravest consequences. These avalanches are difficult to anticipate and manage. Use extra caution when crossing the tracks and runouts of avalanche paths and where you are exposed to overhead avalanche terrain. Wet Slabs could start at upper elevations and run long distances into lower elevations.

 You are most likely to trigger or see Wet Loose avalanches. Many of these slides ran in the past couple days. The Wet Loose avalanche cycle is tapering off below treeline, but will continue at upper elevations. While these avalanches may be the smallest and most predictable of today’s problems, they could still be forceful or large enough to injure or bury you. Avoid traveling through or above terrain such as or cliffs, gullies, or rocky slopes where the consequences of being caught in an avalanche could be increased.

Cornice fall and Glide avalanches have become possible due to rain and rising temperatures. Both could be very large and dangerous. Avoid areas with visible glide cracks or where known rock slabs underlie the seasons snowpack. Give yourself an extra wide margin of safety near ridges that could hold cornices, and avoid slopes with cornices overhead.

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.