Avalanche Forecast

A transitory ridge of high pressure should move across the area Saturday to allow for cool weather, light winds and some possible sun breaks. This weather should allow for a slow improving trend as recent storm and wind slab slowly settle and strengthen. 

Avoid terrain where wind may have built isolated wind slab layers, mainly higher elevations near ridges, most likely on a wide variety of aspects..    

Avalanche problems Saturday should continue to be associated with recent storm and wind slab layers. Avalanches should be confined to the new storm snow since Thursday, but a few may step down to older storm layers or crusts in isolated locations.  

Terrain anchors are still causing significant anchoring at the lowest elevations. Use caution near creeks which are still open in some areas.

A series of cool storms over the past 10 days following the December 7-8 major rain event, have deposited increasing storm snow at relatively low freezing levels.

The dominant avalanche problems currently remain from storm slabs and wind slabs. Periods of heavy snowfall Thursday and early Friday quickly built unstable storm snow conditions, especially in the Snoqualmie and Stevens Pass area, both Thursday and Friday. Strong winds also built wind slab layers on a variety of aspects due to terrain channeling and redirecting local winds.    

These storm and wind slab problems caused extensive avalanches, both natural and triggered. The great majority of the reported recent soft slab avalanches have released on storm snow interfaces mainly in the upper 8-12 inches of snow. In the Snoqualmie Pass area a brief freezing rain crust was deposited Thursday morning and many slides have released to this layer. A few larger slides up to 2 feet were seen with larger explosives at Alpental Friday, mainly initiating in recent layers and breaking to older storm snow layers. No slides have been reported releasing to the December 9 crust interface which remains strongly bonded.

The Cascade pass areas were protected from the warm up Thursday afternoon by cool east flow and this maintained precipitation as snowfall to the valley bottoms. However, other areas experienced a warm up and rain up to about 6200 feet in the Crystal and Paradise area, lower in the north and to near or above 7000 feet in the south. This is forming a new crust layer with shallower storm snow above.  

There was a party of two caught and injured in the Alpental Valley Thursday near midday at the height of the increased storm slab instabilities. Fortunately, no major injuries or worse occurred.

A good time to review just what the North American Public Avalanche Danger Scale definitions are during CONSIDERABLE danger, especially during a noted increasing danger trend.