Avalanche Advisory for Sunday, December 30, 2007 at 6:15 am By Eric White The Details: This Season: We had a few early season hints of snow in October, then a dry spell with December starting to show signs of winter. Our precipitation is around 86% of normal. We currently have around 2-3 feet of recent snow on a thin old snow surface. We are in a "La Nina" climate condition which often means wetter than normal winters in our area and expectations are for above normal precipitation into the spring of 2008. Weather Observations: We have partly cloudy skies with a half inch to 3 inches of new snow in the surrounding mountains and it is currently 33F in town. Mt. Shasta - We have 35 inches of snow on the ground near tree line with 1 inch of new snow over the last 24 hours. The snow settled 1 inch in the last 24 hours and temperatures have ranged between 20F and 28F at 7000 ft. and it is currently 20F. Winds this morning at tree line were estimated at around 30-35 mph from the W, and 15-20 mph from the W below tree line. On the upper mountain winds are estimated this morning at 90 mph from the W. Castle/Mt. Eddy - Mt. Eddy received 3 inches of new snow in the last 24 hours with 1 inch of settlement. Temperatures were between 20F to 30F over the last 24 hours. We estimate around 2 ft. of snow on the ground with brush showing. Castle Lake is around 16F this morning. Weather Forecast: The cold front has moved in overnight bringing partly cloudy skies with a chance for snow showers today with little to no accumulation. High pressure just off the coast will be keeping us dry for the next few days into the New Year. At mid elevations today, temperatures will warm to the upper teens to mid 20's. Below tree line, winds will be fairly light from the NW, moving overnight to the ENE. Above tree line, winds will be 25-30 mph from the WNW. On the upper mountain, winds will be 60-70 mph from the WNW, slowing to 40 mph tomorrow morning from the NW. A series of strong storms are expected during the second half of this week, beginning Wednesday night, with an interesting mixture of very cold air and tropical moisture. The central and southern Sierra's look like they will get most of the precipitation from this event. Wet weather should continue into the middle of January. Snow Pack: We have "dust on crust" again today with the best conditions below tree line. Above tree line winds have left a mixture of scoured rocky slopes and wind slabs. Snow below tree line remains fairly thin and I found a few rocks yesterday so be careful! Yesterday, Nick and I found shooting cracks and small, thin wind slabs at and above tree line, releasing easily. The slopes above tree line with the most snow are ones loaded by the wind and most likely to avalanche. In our stability tests we found failures with easy to moderate force in the new snow and wind slabs. Don't let the sunshine today lure you into wind loaded slopes! Some important thoughts: This advisory does not apply to Ski Areas or Highways and is for the Mt. Shasta, Castle Lake and Mt. Eddy back country. Use this information for guidance only. You may find different conditions in the backcountry and should travel accordingly. This advisory expires at midnight tonight. As always, use safe travel practices: travel with a partner, travel one at a time in suspect areas, go from one island of safety to another, choose safe routes, wear a transceiver, carry a shovel and probe, and know how to use your gear!