Avalanche Forecast

You could trigger loose avalanches on steep shaded slopes and northerly aspects near and above treeline. Triggering avalanches in the surface snow is possible on slopes approaching 40 degrees and steeper. Use extra caution when traveling in very steep near terrain traps such as gullies, rocks, and cliffs. Even small avalanches could injure you if they push you into these features.

About 10 inches of snow fell on Wednesday with light accumulations adding small amounts throughout the week. Cold temperatures at upper elevations have kept this snow soft and lacking cohesion. Use small test slopes to see if the surface snow slides under your boards or machine. 

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.

Large cornices loom on most high ridges from many westerly wind events this winter. With stronger sun on Monday, the chance for cornice fall may increase. That said, falling cornices can be difficult to predict. Observers have reported sporadic cornice fall over the past couple weeks. The most recent report was a D2.5 avalanche in the Hairpin valley that was triggered by a falling cornice on February 29th. Use caution to not travel on or under overhung cornices. Consider avoiding terrain where overhead cornices are exposed to direct sun. Be aware of overhead cornices even when you are well-below ridge-tops.

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind lips of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

Cornices can never be trusted and avoiding them is necessary for safe backcountry travel. Stay well back from ridgeline areas with cornices. They often overhang the ridge edge can be triggered remotely. Avoid areas underneath cornices. Even small Cornice Fall can trigger a larger avalanche and large Cornice Fall can easily crush a human. Periods of significant temperature warm-up are times to be particularly aware.

A corniced ridgeline. A large cornice has formed at the top of the ridge. A smaller cornice has formed to the left of the trees from crossloading.

Cornices are easy to identify and are confined to lee and cross-loaded ridges, sub-ridges, and sharp convexities. They are easiest to trigger during periods of rapid growth (new snow and wind), rapid warming, and during rain-on-snow events. Cornices often catch people by surprise when they break farther back onto flatter areas than expected.