This is Janet Kellam of the Sawtooth National Forest Avalanche Center
 with your Backcountry Avalanche Advisory and Weather Forecast for
 Friday, January 4, 2008 at 7:30 am.

 Idaho Department of Parks & Recreation in partnership with Idaho's
 Snowmobile License Plate Program & the Friends of the Sawtooth
 Avalanche Center bring you this advisory.

 Bottom Line:
 The avalanche danger begins as MODERATE this morning, increasing
 to HIGH danger by tonight or tomorrow morning. Anticipate changing
 conditions throughout the day and into the weekend.

 A powerful winter storm is forecast to impact our area with heavy
 snowfall, strong winds and warm temperatures.

 If the storm materializes as forecast, avalanche conditions will
 develop throughout our region. Wed like to issue a special heads up
 for the Central and South Valley and areas with a thinner snowpack.

 These areas consist of very weak snow. Avalanche danger will increase
 rapidly at upper elevations in these locations once we get 6 to 10
 inches of snow accompanied by wind.

 Primary Avalanche Concern:
 
 
 
 
 Central and South Valley: These areas consist of a weak, shallow
 snowpack. Any new snowfall will produce an unstable slab and
 avalanches will become likely, especially human triggered. Rapid
 accumulations of snow, warm temperatures and strong southerly winds
 mean conditions may change quickly. Due to the nature of the weak,
 faceted snow on the ground this instability will be with us for
 awhile. The South Valley has such little snow the avalanche danger
 will primarily be confined to north facing and upper elevation slopes,
 or slopes where the sagebrush is covered, unless we get more than a
 foot of snow.

 North Valley, Salmon Headwaters and areas with a deeper snowpack:
 These locations have a generally stronger snowpack but weak pockets do
 exist, especially in high alpine regions or in steep, rocky terrain.

 Human triggered slides have been reported as recently as two days ago
 on steeper upper elevation slopes.

 In addition, these more mountainous areas may get greater amounts of
 snow. We are concerned about weak snow existing on and near the old
 surface of the snowpack that will become overloaded with the warm and
 windy storm.

 Secondary Avalanche Concern:
 
 
 
 
 This storm promises to be intense, with rapid rates of precipitation,
 warm temperatures and strong southerly winds. This means the new snow
 itself will be top heavy and unstable at least for a day or two.

 Northerly facing slopes will be the most suspect due to windloading
 from southerly wind but watch for wind drifting and cross loading in
 just about any area. Yesterdays ridgeline winds may have developed
 shallow wind slabs already, by drifting old surface snow onto leeward
 slopes.

 Current Conditions:
 Partly starry skies when I came in this morning have turned to mostly
 cloudy before dawn. It is almost hard to believe we will get socked
 with a strong winter storm by afternoon, but all indications are
 favorable to get a wild and woolly snow-producer.

 Yesterday, strong southeast winds ahead of the front averaged 20mph at
 upper elevations and gusted up to 49mph. They have calmed down a bit
 this morning and shifted to the southwest as the storm enters our
 region, but continue to gust 20 to 30mph.

 It appears that Galena Summit and the Sawtooths may just be beginning
 to get light snowfall by 6AM.

 Temperatures at upper elevations were quite warm yesterday, near 30
 degreees, and are currently in the low twenties. The valley bottoms
 warmed up from near zero degrees to around thirty degrees. Ketchum
 reports 18 degrees at 6AM and Stanley reports a tropical 27 degrees,
 getting more of the warm air from this weather system.

 Mountain Weather Forecast:
 There is a 100% chance of snow today and tonight. Three to four inches
 of snow is expected today in the mountains, 10 to 12 inches overnight
 and an additional 3 to 6 inches Saturday morning. Because of the
 extent of the storm system and the favorable southwest flow, we may
 get more than that.

 Winds are forecast to increase during the storm, blowing an average of
 25 to 35mph from the south, increasing to 35 to 45mph with stronger
 gusts.

 Temperatures are expected to reach 20 to 25 at upper elevations and
 over 30 degrees on the valley floor. This means we may see a mix of
 rain & snow at our lowest elevations. Temperatures are expected to
 cool tonight to 15 to 20 degrees at upper elevations, 20 to 28 degrees
 on the valley floor.