This is Matt Lutz of the Sawtooth National Forest Avalanche Center with your Backcountry Avalanche Advisory and Weather Forecast for Thursday, December 20, 2007 at 7:30 am. The Sun Valley Telemark Series & the Friends of the Sawtooth Avalanche Center bring you this advisory. Bottom Line: Today the avalanche danger is estimated to be MODERATE with isolated areas of CONSIDERABLE on steep terrain and exposed ridgelines due to wind deposited snow and increasing temperatures. The snow totals over the last 5 days within the heart of our forecast area are between 10 to 16 inches, with some areas of the northern Sawtooths receiving up to 30 inches. This new snow has fallen on a widespread weak old snow surface. Expect changing conditions today as our forecast area is expected to see up to another 6 inches of snow in the mountains, moderate westerly ridge top winds and relatively warm temperatures. Primary Avalanche Concern: Over the last 4 to 5 days our forecast area has continued to receive small impulses of snow. The Central and North Valley have received around 12 to 16 inches at higher elevations. The Sawtooth Mountains and Salmon River Headwaters areas have received around 2 feet and the northern Sawtooths upwards of 30 inches. All this new snow has fallen on a weak old snow surface. Though the new snow totals are starting to get more impressive the snow pack has had time to adjust to the new load. I do not expect widespread instability within the new snow with the exception of steep terrain and/or high elevation ridgelines where wind deposited snow has accumulated. Today the temperatures are expected to be close to freezing. If the snow turns to rain the avalanche danger will rise rapidly. This is more likely at mid to lower elevations but be aware that near freezing temperatures could help the new snow act more as a slab even at elevation. Secondary Avalanche Concern: The wind over the last few days has been just strong enough to move snow around the tops of exposed higher elevation ridgelines. Today we may see a generally increasing wind trend that could cause further wind slab development and increasing danger. Expect new and recently buried wind slabs on north, northeast and east aspects. Watch for cornice formation, cracking, whumpfing, and natural avalanche activity as signs of instability. Additional Discussion: The snow on the ground prior to this last storm cycle was quite variable, but did have one common theme through out our forecast area. That common theme was a very weak snow surface caused by near surface faceting. In areas of the Central and North Valley below approximately 8500 feet the snow was generally less than 3 feet deep. In these areas the entire snow pack was faceted (i.e. sugary) and weak. In the Sawtooth Mountains, Salmon River Headwaters, and North Valley above 9000 feet where there was generally more than 3 feet of snow, the deep snow pack was more consolidated. These areas with a deeper snow pack still generally have a faceted sugary layer near the ground. This could still be a factor if enough snow load is applied. Current Conditions: Nice soft snow riding conditions exist throughout our forecast area. The snow pack in the South and Central Valley is still very thin. The North Valley and Sawtooth zones have a deeper snow pack where good riding conditions abound. Ridge top winds are currently light to moderate out of the southwest. Ridge top temperatures are hovering around 20 degrees. Mountain Weather Forecast: The weather forecast today calls for a few more inches of snow, light to moderate winds out of the southwest this morning, shifting to the northwest by mid afternoon. Expect an increasing wind trend through the day. The temperatures are expected to be fairly warm with the possibility of a rain snow mix at lower elevations. A cold front should move into our area by later tonight. Please Note:The Nat'l Weather Service is having problems with weather station website data, we hope to have our Titus, Lower Titus and Baldy stations display more current data soon. Soldier Mtn is working on repairing their wx station.