Avalanche Forecast
Regions: Cascades - West.
The avalanche danger will be listed as low at all levels due mainly to strong surface crusts or low snow cover.
Detailed Forecast
An upper ridge will weaken slightly, but remain over the region Saturday. This will cause light winds, sunny weather and mild temperatures. High clouds should move in during the day a weak frontal system approaches.
Cooler east winds in the lower Cascade passes should maintain periods of low clouds or fog, especially in the valleys east of the crest with fog reaching Snoqualmie at times.
This weather will cause little change in snow conditions and the low snowpack will cause an overall low danger. The only limited avalanche problem to watch for should be loose wet avalanches above treeline. But the likelihood and size will be listed as unlikely and small respectively
Snowpack Discussion
Last weekend a warm front caused high snow levels and rain. Most NWAC sites west of the crest had about 1-3 inches of rain. This caused loose wet avalanches, some possible wet slab avalanches and consolidation. West of the crest a lot of water was seen in and draining from the snow pack.
This week, high pressure aloft has caused abundant sunshine and mild temperatures, generally well into the 40's and at times lower 50's.
The snowpack is therefore dominated by strong surface crusts, limiting the avalanche potential. There has been some surface hoar growth over the past few clear nights and this may be preserved on sun shaded terrain and mainly found below about 5000 feet, and especially at lower elevations where more fog or low clouds have formed.
NWAC forecaster Dennis D'Amico found previous loose wet avalanches on Monday on this SE aspect at about 6500 feet in the Paradise Glacier Valley, possibly triggered by small cornice drops during the weekend rain event. Here are a couple of his photos.
The snowpack west of the crest should mainly consist of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
Avalanche Problems
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.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood: Unlikely
Expected Size: 1 - 1