Avalanche Forecast

Storm slabs may be present in all elevation bands on Sunday, as freezing levels hover around 4000 feet. Slabs may be drier and deeper as you ascend in elevation or in areas where winds have deposited new snow on leeward slopes. With the weather pattern favoring the volcanoes, you may find lesser snow totals in areas such as Crystal and White Pass, and therefore smaller slabs. Observations Saturday reveal that a surface crust has developed in many locations in the zone for any new snow to fall on. Use small test slopes and hand pits to investigate the bond between the new snow and the existing surface. If you find a poor bond and more than 6 inches of cohesive snow, avoid slopes greater than 35 degrees.

Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.

Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.

We have had a notable wet avalanche cycle the past week, with Wet Loose, Wet Slab, and Glide avalanches all being observed, and often intermingled. Realize that liquid water still remains in the snowpack in many locations and be leery of big terrain features or unsupported slopes that did not slide in the previous cycle.

Below ~4000 feet Sunday, precipitation may fall as rain causing wet loose avalanche conditions to develop yet again. Wet Loose avalanches often start at a point and can entrain lots of snow as they travel downhill, even triggering slabs as they descend. Rollerballs, pinwheels, and fan-shaped avalanche debris are signs that wet loose avalanches are possible. Steer around slopes greater than 35 degrees and avoid terrain traps such as creeks, gullies, or cliffs if you notice these signs or witness a switch from snow to rain. 

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.