16 December 2006

 Good morning. This is Ron Johnson with the Gallatin National Forest
 Avalanche Advisory issued Saturday, December 16 at 7:30 a.m. 

 WEATHER

 Yesterday a quick moving weather disturbance deposited 4-6 inches of
 snow in the mountains around Bozeman and Big Sky. Six to eight inches
 accumulated in the mountains around Cooke City, while the mountains
 around West Yellowstone got 2-4 inches. As the disturbance passed
 through, mountain temperatures dropped from morning readings in the
 low 30s F to afternoon readings in the teens F. Yesterday, westerly
 winds raked the ridgetops at 20-40 mph with gusts exceeding 60 mph.

 This morning, at 4:00 a.m., mountain temperatures were in the single
 digits F, and west-southwesterly ridgetop winds were 20-30 mph, though
 gusts over 70 mph were recorded in the Bridger Range. Today, westerly
 ridgetop winds will continue to blow 20-30 mph and mountain
 temperatures will reach the teens F. A weak weather system will
 produce scattered snow showers over the northern mountains. New snow
 accumulations will be less than an inch.

 SNOWPACK AND AVALANCHE DISCUSSION

 The mountains around Cooke City and the Washburn Range:

 Yesterday, at least one large avalanche released in the mountains
 north of Cooke City. This week, almost 4 inches of snow water
 equivalence was added to the snowpack in this area. This combined with
 strong winds has created a HIGH avalanche danger on wind-loaded
 slopes steeper than 35 degrees. A CONSIDERABLE avalanche danger
 exists on less steep wind-loaded slopes; while non-wind loaded slopes
 have a MODERATE avalanche danger.