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Avalanche Forecast

Archived

Dec 29th, 2014–Dec 30th, 2014

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.

Storm slab instabilities should continue to settle out Tuesday but may still be touchy. Also, recent N-NE winds will have loaded southerly aspects so make sure to evaluate wind loaded terrain. Moderate avalanche danger means human triggered avalanches are possible! 

Detailed Forecast

Tuesday should be mostly sunny with light winds. Temperatures should remain cool.  The biggest avalanche problem should be new and lingering wind and storm slab formed over the weekend through Monday. More recent northerly winds likely redistributed snow on more southerly aspects above and near treeline. With the recent low density snowfall, sheltered terrain may present a loose dry avalanche problem on steeper slopes near terrain traps. 

 

 

 

Snowpack Discussion

The Olympics have finally received enough snow to warrant avalanche forecasts for the season. NWAC observer Tyler Reid confirmed on Friday there is now sufficient snow to produce avalanches. Here is a short video from Tyler at Hurricane Ridge on Friday:

A storm system over the weekend only deposited about 6 inches at Hurricane Ridge through Sunday morning. Persistent snow showers Sunday and Sunday night deposited at least another 6 inches of low density snow.  Pro-observer Tyler Reid found touchy storm slab remaining on all aspects Monday at Hurricane Ridge.  Also, moderate westerly transport winds became northerly Sunday night through Monday... likely building shallow and new wind slab on more southerly aspects.   

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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 Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.