Avalanche Forecast

You may encounter recently drifted and stiffened snow on upper elevation slopes and wind-exposed ridges. Pay attention as you gain elevation and transition into wind affected terrain. Look for obvious signs of wind drifted snow like cornices, lens-shaped pillows, and textured snow surfaces. Feel for hollow sounding snow and watch for shooting cracks as you travel. Be leery of unsupported slopes and convexed roll-overs. Stick to lower elevation terrain and wind-sheltered areas to avoid the problem. Use visual clues to identify wind drifted areas, and small test slopes to determine how easily you could trigger an avalanche.

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.

A chance of light rain, brief periods of filtered sunshine, and rising freezing levels (6000ft) could all drive a round of loose wet activity Thursday. If you see new rollerballs or find fresh fan-shaped debris, avoid traveling on similar slopes. Even small loose avalanches could have high consequences if they push you into a creek, over a cliff, or trigger slab avalanches as they run downslope. Stay aware of slopes above you, especially if the sun comes out or if you witness rain on dry snow.

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.