This is Chris Lundy of the Sawtooth National Forest Avalanche Center with your Backcountry Avalanche Advisory and Weather Forecast for Sunday, February 24, 2008 at 7:30 am. The Twin Falls District Bureau of Land Management & the Friends of the Sawtooth Avalanche Center bring you this advisory. Bottom Line: Today the avalanche danger is estimated to be HIGH on wind loaded slopes and CONSIDERABLE on slopes sheltered from the wind. 6-10 inches of new snow has fallen overnight and more is expected to accumulate today. Todays new snow will likely be poorly bonded to the old snow surfaces on many slopes. Avalanches will be likely on exposed leeward ridgelines and other terrain features where strong southerly winds are transporting the new snow. Unstable conditions will continue to develop through the day as more snow accumulates and strong winds continue to load leeward slopes. Primary Avalanche Concern: Right on cue, southerly winds began increasing last night the moment the snow started to fall. Strong winds combined with low density new snow means that fresh wind slabs will be widespread on upper elevation exposed terrain. These wind slabs will likely be poorly bonded to the fluffy snow beneath and I expect they will be very sensitive today. Stronger winds will continue through much of the day, so wind drifts will continue to build and may become more unstable as the day progresses. Secondary Avalanche Concern: Overnight, a significant dose of new snow fell in our southern mountains, while our northern area picked up a bit less. This morning, I would expect that unstable conditions already exist in the South and Central Valley. In the North Valley, less snow has fallen but the danger will rise through the day as more snow accumulates. Use extra caution anywhere where 12 inches or more of new snow has accumulated. Todays new snow is falling on a mixed bag of old snow surfaces. On sheltered northerly aspects the old snow surface consists of sugary near surface facets, especially in our southern mountains. Slick crusts exist on sunny aspects, and in many places these are covered with a few inches of dust from Friday nights storm. Many other possibilities exist, but the common theme is that the new snow will likely be poorly bonded to the surface it is falling on. High precipitation rates and increasing temperatures during the storm will likely add to the unstable nature of the new snow. With two weeks of dry conditions, todays powder will be very tempting. I know how you feel; Im having a hard time sitting here at the computer writing this. But until we see how the snow is behaving, it will be a good idea to stick to lower angled slopes. Get your hands in the snow - with such fluffy new snow it will be easy to dig down to the old snow surface. Isolate a block of snow and see how well it is glued on to the snow beneath it. Use extra caution wherever the old snow surface seems sugary or consists of a hard crust, and pay attention to the usual warning signs such as collapsing or cracking of the new snow. Current Conditions: Snowfall started around midnight last night and as of 6am this morning, about 8-10 inches of snow has fallen in the upper elevations of the South and Central Valley, and our northern area picked up around 6 inches. In Ketchum, the new snow has a density of about 5%. Ridgeline winds increased to 20-30 mph from the south to southeast, with gusts into the upper 30s and 40s. Temperatures at the higher elevations are in the upper teens to low 20s, and its currently 27 degrees in Ketchum. Mountain Weather Forecast: The low pressure system responsible for last nights snowfall is already breaking apart, but 4-6 inches of additional accumulation is possible during the day. Ridgeline winds will continue at 15-25 mph from the south to southwest before easing later today. Mountain temperatures are forecasted to reach the mid to upper 20s, and a high of 32 degrees is expected in the valley.