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Avalanche Forecast

Archived

Jan 12th, 2018–Jan 13th, 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.

Regions

Olympics.

Wind slabs formed on a variety of aspects Thursday. Look for and avoid areas of wind deposited snow such as fresh cornices and snow drifts. Keep an eye on changing surface conditions as mild weather and clearing skies allow sunny slopes to develop the potential for loose wet avalanches.

Detailed Forecast

After a drippy and and cloudy start, warm air temperatures, light winds, and partially clearing skies in the afternoon will allow moist surface snow to develop on sunny slopes Saturday. Keep an eye out for signs of loose snow instability such as rollerballs and pinwheels. These can be a sign that conditions are becoming prime for loose wet avalanches.

Near and above treeline, wind slabs formed Thursday are expected to linger. While they are gaining strength, take time to identify and avoid areas where winds have deposited snow.

Despite the recent snow, early season hazards still exist. Many creek beds have still not filled in for the winter.

Snowpack Discussion

Very light precipitation and mild temperatures on Friday allowed storm snow layers to continue to gain strength. Ridge top winds continued to redistribute snow especially in the above treeline areas.

About of foot of recent snow is bonding to the most recent rain crust which exists in sheltered terrain around Hurricane Ridge. Below this rain crust, no notable layers of concern have been identified within the snowpack.

The height of snow across the terrain is quite variable with low snow in many areas below treeline. Numerous obstacles still exist at all elevations.

Observations

NPS Rangers Friday morning reported small natural loose wet avalanches visible on road cuts up to 4500 feet on the Hurricane Ridge road.

NWAC pro-observer Matt Schonwald was at Hurricane Ridge on Thursday 1/11. Matt found despite the significant storm snow, below treeline elevation band had quite variable snowcover.  Around Hurricane Ridge, the east slopes had a snow depth of 2.5 feet and the west slopes had about 5 feet. Winds were actively transporting new snow near and especially above treeline, but the loading pattern was variable. Small loose wet avalanches were observed releasing in steep terrain above the road at about 4500' during gradual warming on Thursday.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.