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Avalanche Forecast

Archived

Mar 31st, 2017–Apr 1st, 2017

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.

Loose-wet snow avalanches should remain possible in steep terrain. Use caution in steep terrain, especially if the surface snow is wet more than a few inches, avoiding steep slopes above terrain hazards such as trees or cliffs. Avoid travel on or below cornices.

Detailed Forecast

A warm sunny day Friday allowed for further shallow melt and consolidation. Increasing clouds Friday night with light precipitation should maintain mild temperatures and allow for limited surface crust formation.

This weather should maintain shallow, moist to wet surface snow conditions Saturday.

Only light amounts of additional precipitation with a gradual cooling trend are expected Saturday. This should not appreciably change the overall avalanche danger through the day Saturday.

Expect shallow wet snow conditions over one or more strong near surface crust layers.

Any recent shallow wind slabs should have mostly stabilized where formed on lee slopes, mainly above treeline and on NW-SE aspects.

Recent cornices are very large. Natural cornice releases and resulting slab avalanches are dangerous and unpredictable. Give cornices a wide berth if traveling along ridge-lines and avoid slopes directly below large cornices. See a blog post regarding cornices here. 

Snowpack Discussion

Weather and Snowpack 

The first week of March was very cool and snowy, followed by significant periods of heavy rain in the second week of March. This caused significant avalanche cycles in most areas March 9-10. Significant snowpack consolidation occurred over this period due to rainfall and warmer temperatures. 

Several additional inches of rain fell on the west slopes of the Olympics and Cascades on Friday, 3/17 through early Saturday morning 3/18. Rapid cooling following the rain event 3/18-19 has formed a very strong crust layer, now buried by snowfall in late March. Surface snow has undergone several additional melt-freeze cycles over the past week.

The dominant wind pattern for the last several frontal systems have been moderate sustained S-SE winds. This has transported available snow to build fresh wind slabs in the Hurricane Ridge area.

Daily early spring warming temperatures have allowed surface snow melt and consolidation, at nearly the same rate as accumulations. Since March 23rd, the Hurricane area has received about 2 feet of snowfall with the total snowdepth only increasing by about 8 inches as of Friday evening, 3/31, going through several melt-freeze cycles and leaving a strong surface crust. 

Recent Observations

No recent observations. 

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.