Mt Hood

Exercise caution and expect potentially dangerous avalanche conditions on wind loaded slopes above the treeline Thursday.  

Isolated snow showers, sun breaks, light NW winds and cool temperatures should do little to change the avalanche danger Christmas Day.

However wind slabs on lee slopes near and above treeline should continue to be sensitive to human triggering and should be avoided. NW winds likely continued to load lee slopes Wednesday night.  Newly formed corncies should also be given a wide berth.  In general, exercise caution and expect potentially dangerous avalanche conditions on wind loaded slopes above the treeline Thursday.  

A warm plume of moisture moved over the Pacific Northwest last weekend. Especially strong winds and heavy precipitation were recorded at Mt Hood; 9-12 inches of water fell at NWAC stations over 72 hrs ending 4 am 12/22 along with frequent gusts over 100 mph in the alpine, wow! A natural avalanche cycle likely occurred on the upper mountain.   

The frontal system that impacted the area Tuesday evening through Wednesday started warm and ended cold for a right side up layering. New snowfall amounted to only a few inches at NWAC stations by 4 pm Wednesday, but moderate to strong winds turned northwesterly with the cool-down... loading easterly aspects during the day. Winds were SW at the onset of this storm... and above treeline slopes were likely cross loaded. 

New NWAC pro-observer C.J. Svela reported substantial wind transport Wednesday in White River Canyon in the near and above tree-line elevation bands.  This translated to cracking on wind loaded slopes and sensitive cornices in the canyon.  He also reported a break-able crust below the most recent snow.