Avalanche Forecast

Significant precipitation and rising snow levels Monday night into Tuesday morning should form fresh and reactive storm slabs. The recent snow sits above a crust that should be gradually refreezing to form a bed surface.  Consequently, you could trigger an avalanche on any slope greater than 35 degrees. In areas where the wind drifts the snow deeper, avalanches could be larger. New storm snow will accumulate on a light and relatively weak surface from early Monday. One of the big questions is how will the new snow bond to the surface? We think the light snow from Monday could act as a weak layer or, at the very least, be entrained in an avalanche. Take time to look in the snow. Small hand pits, hand-shear tests, or small slope tests could give you the best idea of how the snow may respond to a trigger. As of Monday afternoon about a foot of soft dry snow rests over a prominent crust (1/24) in the nearby Mt. Baker backcountry and the depth should be significantly lower (5-8” estimated) in most of this zone. Avalanche concerns should be limited to the upper snowpack above the crust.

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 think the E flow during this storm will have less of a leg to stand on in this zone than in the Passes and West North zones as a subtle warming trend moves into the region overnight bringing the rain/snow line up to 3500 ft or so. We don’t know exactly how much snow will fall at lower elevations before the likely changeover to rain or when that changeover will occur, but the snow to rain transition is when you can expect the most natural avalanche activity. You can trigger a small Loose Wet avalanche on any slope where you find your boot sinking into wet snow deeper than 6”. Plan your day such that you avoid having to cross larger open slopes greater than 35 degrees to return home safely. Even a small loose wet avalanche can have enough strength to move you into a terrain trap such as an open creek or push you over a cliff.

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.