Avalanche Forecast

Strong winds continue to drift snow both new and old snow into firm, cohesive slabs. These drifts will be deeper and more significant at higher elevations. Check to see how these slabs are bonding with the snow below. Are you experiencing shooting cracks through the snow or hear whumphing collapses? Is the wind actively transporting snow? Look for recent avalanches, and use small test slopes to check how easily the snow can slide.

Some of these slabs have grown large and may not exhibit direct signs of instability before releasing, so think twice before entering any features that appear heavily duned by the wind. More deeply buried weak layers may still be a concern in some areas. Consider the consequences before entering slopes steeper than 35 degrees. Be extra cautious around convex rolls, below ridgelines, and near terrain traps and strainers, such as stands of trees.

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.

Rain on fresh snow over a crust is a great recipe for loose wet avalanches. Wet snow may entrain more wet snow as it moves downhill on steep slopes, creating powerful debris piles. Rollerballs and recent, fan shaped avalanches with ball shaped debris piles are signs that you may be able to trigger these. Stay off of, and out from underneath steep open slopes to avoid these.

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.