Avalanche Forecast

E and NE winds from Saturday night into the day on Monday have stripped many W and N aspects near and above treeline. The wind-deposition zone on unusual S and W aspects now has sensitive slabs on these typically wind-scoured aspects. Old large cornices will not be a good guide to where wind slabs may exist. You'll want to take time to look for and avoid wind loaded pockets on steep slopes below recent small cornices and wind-lips, with smooth pillow-like drifts, or that hold deeper, firmer deposits of snow. With most of the recent snow already transported, you may or may not be able to use actively blowing snow to identify recently loaded slopes. Be aware that some of these slabs may for over pockets of bare rock or thin snowpacks on previously wind-scoured ridges.

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.

Below treeline you can still find light, dry, and unconsolidated snow. As a result, you could trigger generally small loose dry avalanches on slopes steeper than 35 degrees. Some of these slides could run far and fast. Don’t get surprised by these sluffs, knocked off your feet, and pushed into a terrain trap such as a gully, tree, rock, or over a cliff. As temperatures warm slightly in the afternoon, some of this snow may become slightly stickier and less prone to loose dry avalanches.

Release of dry unconsolidated snow. These avalanches typically occur within layers of soft snow near the surface of the snowpack. Loose Dry avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs. Loose Dry avalanches can trigger slab avalanches that break into deeper snow layers.

Loose Dry avalanches are usually relatively harmless to people. They can be hazardous if you are caught and carried into or over a terrain trap (e.g. gully, rocks, dense timber, cliff, crevasse) or down a long slope. Avoid traveling in or above terrain traps when Loose Dry avalanches are likely.

Loose Dry avalanche with the characteristic point initiation and fan shape.

Loose dry avalanches exist throughout the terrain, release at or below the trigger point, and can run in densely-treed areas. Avoid very steep slopes and terrain traps such as cliffs, gullies, or tree wells.