Avalanche Forecast

Archived

Apr 26th, 2018–Apr 27th, 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 avalanche hazards will persist on Friday. You can trigger a Loose Wet avalanche that can gouge deeply and gain mass rapidly in soft, poorly bonded snow. Give cornices a wide buffer while traveling on ridges and avoid spending time on slopes below them.

Detailed Forecast

You can still trigger Loose Wet avalanches on slopes over 35 degrees. Expect Loose Wet avalanche danger to peak during the late morning hours as solar radiation warms the snow before clouds and westerly winds bring cooler conditions later in the day. If you sink in wet snow up to the top of your boots, avoid slopes over 35 degrees.

Give cornices a wide buffer. They will break naturally and you could easily trigger them. Cornices will often break surprisingly far back from the edge. Make sure you are well off and out from under cornices, especially as the sun is shining on them. Cornice fall, while dangerous on its own, could trigger Loose Wet avalanches. While cornices are generally reported to be small, assess the size and your exposure to each one as you travel through the terrain.

Snowpack Discussion

A strong and high pressure has brought very warm temperatures to the Olympics from Monday through Thursday. Temperatures at Hurricane Ridge have not fallen below freezing since Sunday night (4/22). The shallow or non-existent surface refreeze likely created unstable and poorly bonded snow within the upper 1-2 feet of the snowpack.

An inch or two of new snow with moderate south winds Friday night transitioned to partly to mostly cloudy skies with cool temperatures in the Hurricane Ridge area Saturday with no reported storm-related avalanche activity.

Aided by the recent warm weather, the Olympic snowpack has consolidated 2 ft since it's season maximum near and above treeline on 4/17.

Observations

A National Park ranger flew over the Blue Glacier on Mt. Olympus on 4/25 and observed small Loose Wet avalanches on sun-cooked west-facing slopes with no other avalanches observed.

NWAC pro-observer Matt Schonwald visited the Hurricane Ridge area 4/20 and reports no significant layers of concern within the snowpack and generally small 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.