This is Chris Lundy of the Sawtooth National Forest Avalanche Center
 with your Backcountry Avalanche Advisory and Weather Forecast for
 Tuesday, December 18, 2007 at 7:30 am.

 The Wattis Dumke Foundation & the Friends of the Sawtooth Avalanche
 Center bring you this advisory.

 Bottom Line:
 Today the avalanche danger is estimated to be MODERATE. A storm
 system arriving this afternoon will begin to load a widespread weak
 snowpack, and the avalanche danger will likely rise by tomorrow
 morning. If this storm kicks in earlier than anticipated, the
 avalanche danger may rise as early as this afternoon, especially in
 the Salmon Headwaters and Sawtooth Mountains where greater snow
 accumulations occurred yesterday.

 Yesterdays new snow and southwest winds combined to form small but
 sensitive wind slabs along leeward ridgelines. Use caution today in
 exposed upper elevation terrain where these wind deposits will likely
 remain a concern.

 Primary Avalanche Concern:
 
 
 
 
 Yesterday I found that the new snow was being transported by steady
 southwest winds. On north through east facing upper elevation
 ridgelines, small wind slabs would release when ski cut. These fresh
 wind pillows will be most significant in areas that received greater
 accumulations of new snow yesterday and will likely remain sensitive
 today.

 Secondary Avalanche Concern:
 
 
 
 
 Anywhere you go in our region, youre going to find faceted snow of
 some variety. Where the snow is less than about 2 feet deep, two weeks
 of cold, dry conditions have turned the entire snowpack into
 cohesionless sugar. Where the snowpack is deeper than this, the
 primary problem is faceting that occurred on the snow surface.

 I was in the Salmon Headwaters region yesterday where the snowpack is
 generally 3-4 feet deep. Here the primary concern was loose, sugary
 snow below the 6 inches of new fluff. While the new snow was not yet
 behaving as a slab, I could still get it to shear easily on the old
 snow surface. Not quite a problem yet, but it gave me an idea of what
 to expect once we start adding more snow.

 I expect that tonights storm system will produce enough of a load on
 our weak snowpack that by tomorrow morning we will have unstable
 conditions in many areas. However, I will let Matt deal with that
 tomorrow let's get back to today. The snowfall is expected to kick in
 this afternoon and tonight, but if it arrives faster or stronger than
 forecasted, we may begin to see some early signs of instability by
 later today. Today will be a good day to pay attention to how
 conditions are changing, and anticipate increasing avalanche danger as
 the snow accumulations increase.

 Current Conditions:
 Yesterdays storm dropped 3 inches of new snow on Baldy, 4-6 inches of
 fluff in the Galena Summit area, and upwards of 6-8 inches in the
 Salmon Headwaters and Sawtooth Mountains. The snowfall was accompanied
 by southwest winds blowing steadily at 10-20 mph along upper elevation
 ridges.

 Mountain Weather Forecast:
 A low pressure trough will move through our region this afternoon and
 tonight delivering moisture from the Pacific. By tomorrow morning, the
 South and Central Valley mountains should pick up 4-8 inches of new
 snow, with 6-10 inches expected in our northern area. Temperatures
 should be a few degrees warmer today with mountain highs reaching the
 low to mid 20s. The valley should reach around 30 degrees. Ridgeline
 winds are expected to blow 5-15 mph with gusts in the 20s.

 A stronger system is on this ones heels and should bring more snow to
 our area Wednesday night.