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Avalanche Forecast

Archived

Feb 4th, 2018–Feb 5th, 2018

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

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.

Problems

Loose Wet

Loose Wet avalanches are the 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. 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.

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 drifts 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.