Avalanche Forecast

Expect wet avalanches as rain falls and further wets the upper snowpack. If significant rain totals occur, large natural avalanches could run long distances. You will need to be extra cautious and watch for any overhead avalanche paths where avalanches could run to lower elevation slopes.

Rain falling on dry snow is the perfect combination for large wet avalanches. You will definitely see loose wet avalanches at low elevations and you may see large wet slabs extending to near treeline. Parts of the zone with prominent weak layers or where significant rain accumulates could be prone to wet slab avalanches. This includes the Wenatchee Mountains, the lower eastern Entiat Mountains and any of the eastern foothills. There is much uncertainty around wet slab avalanches and they are very hard to predict. For certain, they can be large and dangerous.

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.

Warm heavy snow will fall at the highest elevations with southwest wind. Wind slabs could be easy to trigger. Avalanches at upper elevations could easily entrain wet heavy snow as they run onto lower slopes becoming more dangerous and destructive. You can find a recent crust buried 1-2 feet below the surface that formed around the MLK weekend. This could also serve as a bed surface for avalanches to slide on.

Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.