Avalanche Forecast

Issued: Apr 27th, 2018 11:00AM

The alpine rating is low, the treeline rating is low, and the below treeline rating is moderate. Known problems include Loose Wet.

Northwest Avalanche Center NWAC, Northwest Avalanche Center

A weak storm is helping to ease the avalanche danger with cool temperatures and cloud cover. You could still trigger Loose Wet avalanches on slopes where you find soft wet snow. Avoid being on or under cornices.

Summary

Detailed Forecast

As the avalanche danger drops, the main concern Saturday will remain below treeline where you could still trigger Loose Wet avalanches. If you sink in wet snow up to the top of your boots, avoid slopes over 35 degrees. While they are generally smaller and easier to predict, Loose Wet avalanches can be dangerous if they push you off cliffs, through rocks, or into gullies.

Cornices and Glide avalanches have been active in the past week. The cooling trend may take an additional day or two to have an effect on these avalanche problems. Avoid stopping under known rock slabs and slopes with visible glide cracks.  Continue to put a wide buffer of terrain between you and any cornices. They will often break surprisingly far back from the edge. Make sure you are well off of and out from under cornices as you travel through the mountains.

Light snow accumulations could be enough to increase avalanche danger slightly by the second half of the weekend.

Snowpack Discussion

A weak storm will bring cooling temperatures, clouds, and light precipitation through the weekend. Previously wet and weak surface snow is gaining strength as it freezes. A long stretch of warm weather and strong sun ushered in spring-like conditions last week. An extensive cycle of Loose Wet avalanches, cornice falls, and Wet Slabs occurred in the past week throughout the Cascades.

Generally, Wet Slabs or slab avalanches entraining wet snow in the past week have occurred in the upper snowpack with a few deeper releases reported. In the Mt Baker area and North Cascades National Park west of the Cascade Crest observers have reported a significant cycle of slabs 3-6 feet (1-2 meters) deep. One observer reported probing a widespread weak layer 3 meters below the surface on the Silver Glacier.

On Friday, Forecaster Dallas Glass toured near Paradise on Mt Rainier. Dallas reported a recent cornice fall, a few Wet Slab avalanches up to size D2, and numerous Loose Wet avalanches. While the upper snowpack was moist to wet, it remained supportive.

On Thursday, Dallas Glass reported a natural cornice fall as well as easily triggering Loose Wet avalanches near the Alpental Valley. Dallas reported that a thin surface crust quickly softened in the morning.

Problems

Loose Wet

An icon showing Loose Wet

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. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. 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.

 

Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.

 

Several loose wet avalanches, and lots of pinwheels and roller balls.

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.

Elevations: Below Treeline.

Likelihood

Possible

Expected Size

1 - 1

Valid until: Apr 28th, 2018 11:00AM