Payette Avalanche Center 03-29-2010 at 7:30 am Summary Today guarantees to be a day of major change across our forecast area. A strong Pacific storm is moving through our area and bringing with it some heavy upper elevation snow and very high winds. While the overall avalanche hazard across the West Central Mountains this morning is at moderate there are going to be several factors that will probably boost us into considerable or even high avalanche hazard by tomorrow morning. Warm temperatures, liquid precipitation and high winds are what we have seen overnight with heavy snowfall and high winds forecasted above 6000 feet today. If you are travelling in the backcountry today wet slides are going to be the main concern in the lower elevations. As the new snow accumulates through the day, wind slabs are going to be a major concern near the ridges, wind deposited wet heavy snow could likely send us into a period of natural avalanche activity on all terrain over 35 degrees today and tonight as the snowpack adjusts to this new load. Avalanche Concern #1: Rain is never a good thing for our snowpack. Overnight, our mountain locations have received between .2 and .6 inches of Snow Water Equivalent. Snotel sites are reporting between 1 and 3 inches of snow out of this moisture, which guarantees a wet sloppy mess out there right now. Temperatures at and above 6000 ft at 5am were in the low to mid 30's across our forecast area. The possibility of seeing wet slides on our lower and middle elevation slopes will be increasing throughout the day today. Pay attention in natural terrain traps or even on steep roadcuts where a wet slide could pile up deep. Avalanche Concern #2: This storm seems a little out of place given its timing and the pattern of most of our winter storm events this year, our colleagues in the Sun Valley area are calling this the Christmas Storm(it just got lost in the Pacific for a few months!). This storm is coming in really strong and while the snowline is starting out pretty high, it promises some heavy accumulations above 6000 feet today and through Tuesday night. Our snowpack has not seen a big load like this since before Christmas, the result is going to be some very touchy conditions throughout our mountains. I think it is safe to bet that we will see a period of natural avalanche activity in the next 24 hours with a good chance that the loading of the new snow could reawaken some of our buried weak layers potentially causing some very deep failures. Tonight we can expect a cooling trend as a cold front brings the snowlines down into the valleys and temperatures will drop as much as 10 degrees by Wednesday. Not only is the heavy snowfall going to be a major concern with this storm but the formation of new windslabs will be a big part of the changing conditions as we already are experiencing high winds out of the South and Southwest. High winds are forecasted to continue through tomorrow. The combination of warm snow, heavy accumulations and high winds are going to create widespread areas of new windslab and some areas of very heavy wind loading, if you are out in the backcountry today or tomorrow tune your avalanche receptors to high, it is time to pay attention to the snowpack again. Recent Avalanche Activity: None reported Weather Rain in the valleys with snowlines around 6000 feet today with the possibility of some thunderstorm activity. High today is expected to be near 40 in the valley today with a low tonight of around 31. The snow line will be falling tonight as a cold front enters our area bringing snowlines down into the valleys. The valleys are expected to get 1-3 inches of snow tonight with an additional 2-4 inches tomorrow. The mountains are expected to get anywhere between 18 and 30 inches of snow in the next 48 hours with temperatures cooling significantly at night and day time temps in the low 30's. There is another storm lined up for the end of the week that looks like it will bring yet more snow to our area.