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Avalanche Forecast

Archived

Jan 12th, 2016–Jan 13th, 2016

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

Regions

Olympics.

Dangerous avalanche conditions are expected in all elevation bands by Tuesday afternoon with human triggered avalanches becoming likely as the storm intensity increases. 

 

Detailed Forecast

An incoming frontal system on Tuesday should largely stall along the Olympics during the day with light to moderate rain and snow for the Olympics increasing during the day along with a warming trend. 

Storm slabs should become increasing unstable during the day Tuesday, with larger slabs possible on lee slopes near treeline. Wind slab is possible mainly above treeline, but will not be listed as a top avalanche problem Tuesday. Shallow loose wet avalanches will become likely Tuesday as snow turns to rain near treeline.   

Dangerous avalanche conditions are expected in all elevation bands by Tuesday afternoon with human triggered avalanches becoming likely as the storm intensity increases. 

 

Snowpack Discussion

Deep storm snow from late December should be settled and stabilized at Hurricane. About 6 inches of snowfall was seen at Hurricane last week.

NWAC pro-observer Matt Schonwald was at Hurricane on Friday and generally found a right side up stable snowpack. Older wind slab was limited to 15-30 cm pockets near ridges and tests indicated little propagation. Matt also observed surface hoar primarily on sheltered north to east slopes. 

Mild snow levels and light to moderate rain up to 5-6000 feet Monday has probably eliminated the surface hoar layer moving forward. 

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 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.