Avalanche Forecast
Regions: Olympics.
Warm weather will create wet surface snow conditions at all elevations. Stay off of steep slopes with wet surface snow where you might trigger a Loose Wet avalanche. Avoid traveling on or below Cornices. Warm temperatures and recent rain will make it more likely for these large blocks of snow to fail.
Detailed Forecast
Light rain and continued mild temperatures on Sunday will maintain wet snow and avalanche conditions at all elevations in the Olympics.
Loose wet avalanches are possible to trigger on steep slopes with wet surface snow. Avoid slopes where avalanches may carry you into dangerous terrain such as over a cliff, into a creek, or down a gully. Watch for new rollerballs and pinwheels as signs that triggering a loose wet avalanche is becoming more likely.
Large cornices exists primarily on NW-NE aspects along ridgelines in the Hurricane Ridge area. Mild air temperatures and rain will make these massive blocks of snow more likely to fail. It is very difficult to predict when and where cornices will fall. Avoid traveling on or below cornices during this mild weekend.
Several glide cracks have been reported recently by NPS rangers. Glide avalanches occur in locations where wet smooth ground surfaces allow the entire snowpack to avalanche. Glide avalanches are highly unpredictable and as their releases generally are not tied to peak warming or rainfall. If you see glide cracks on a slope, avoid traveling on or below that terrain. While you are unlikely to trigger a glide avalanche, a glide avalanche would be large and deadly.
Snowpack Discussion
Saturday morning's sunbreaks and mild temperatures were followed by periods of light rain in the afternoon. Significant snowpack settlement continues to occur in the Hurricane Ridge area with the recent warm and wet weather. On Friday, several natural loose wet avalanches were observed at all elevations.
Large cornices developed during the last two weeks of January along ridgelines near and above treeline.
The recent warm and wet weather has produced glide cracks on slopes with smooth ground surfaces. Observations indicate glide cracks in common locations such as 20th of June, Steeple, and the Steep-and-Icy avalanche paths.
Observations
NWAC pro-observer Matt Schonwald and NPS Rangers traveled in the Mt Angeles areas Friday. They observed moist to wet surface snow up to 6000 feet. Loose wet avalanches were seen releasing during sunny breaks around mid-day. They identified and avoided traveling near or below large cornices.
Avalanche Problems
Loose Wet
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.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1
Cornices
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.
Aspects: North, North East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1