Avalanche Forecast

As the strong March sun shines throughout the day, and freezing levels rise to 4000ft, wet loose avalanches could become a concern on solar aspects. It may not take much solar radiation to affect the recent low-density snow, and for snow surfaces to become wet and weak. Be especially careful of steep rocky slopes facing south and west. Monitor snow surfaces throughout the day, and keep an eye out for roller balls and pinwheels as signs that wet loose avalanches may soon follow. Move to shaded aspects or lower angle terrain to avoid the problem. Sunday may be the slow beginning of a prolonged wet loose cycle that will likely play out over the next several days of increasingly warmer temperatures and sunny weather.

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.

Strong easterly winds redistributed the 4-6in of low-density storm snow from Friday and Saturday into shallow wind slabs at upper elevations. Wind slabs will grow larger and easier to find as you climb up in elevation, and may not be well bonded to a variety of older, slick snow surfaces. Be especially careful if you venture to the eastern portion of the zone (Rock Mountain, White Pine, Chiwaukum Range) where you may be able to trigger deeper avalanches with conditions more similar to the East Central zone. Use small, inconsequential test slopes to check how wind drifts react to your weight. You can also use your pole or quick hand pits to check how slabs are bonding to older snow surfaces. Take time to identify and avoid steep slopes with smooth pillow-like drifts, areas below cornices, or where you find firm hollow snow. Be especially careful around the lee sides of ridges and exposed mid-slope features. In areas sheltered from the wind, new snow may be cohesionless, and loose dry avalanches could occur, running far and fast on steep slopes. Ease into terrain slowly and dial back your terrain selection if you observe recent avalanches, shooting cracks, or whumphing collapses.

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.