Avalanche Forecast

The sunny springtime weather pattern and prolonged wet loose avalanche cycle will continue Saturday. Each evening, cold clear nights help the snow surface freeze and limit the avalanche hazard. During the day, rapidly warming temperatures and strong sun weaken surfaces and drive the potential for more wet loose avalanches. This diurnal cycle will repeat itself again, and Saturday looks to be the warmest day yet with freezing levels rising to 7000ft. 

Time your travel carefully, and keep return routes in mind. The most dangerous avalanche conditions will exist in the afternoon, especially on south and west aspects. When you find wet, unconsolidated surfaces or see roller balls and pinwheels, it’s time to seek out firmer slopes on other aspects, or simply call it a day and head home. Our dry winter snowpack is in transition. As it continues to thaw and adjust, surprising avalanche events in isolated areas are possible. Be leery of large complex sunny terrain during the heat of the day where you’re most likely to see a deeper slab or glide avalanche.

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.

Large cornices loom atop many alpine slopes. Several are beginning to droop, and you could see some of them fall. Choose routes that minimize the amount of time you spend under these unpredictable features. A cornice collapse or other avalanche could trigger slides that break into deeper layers of the snowpack. 

Cold dry snow continues to hang on at higher elevations and in shaded terrain. Pay attention if you cross back into these winter-like areas. A handful of human triggered avalanches have occurred recently on wind loaded slopes at upper elevations. If you’re traveling in the alpine, take time to evaluate terrain for signs of wind loading before committing to steeper terrain.

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.