Avalanche Advisory for Sunday, January 6, 2008 at 6:30 am By Eric White The Details: This Season: We had an early thin snow pack with December bringing near normal precipitation and 3.5 feet of snow along with strong winds above tree line. Our precipitation is around 111% of normal since September 1. A strong storm series in early January deposited 4-8 feet of snow with huge wind drifts. 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 mostly cloudy skies and 3-9 inches of snow over the last 24 hours in town this morning. It is currently 28F in Mt. Shasta and 33F in Dunsmuir. Mt. Shasta - We are measuring 71 inches of snow on the ground near tree line with 6-10 inches of new snow over the last 24 hours. We have a storm total of 5-7 feet. 7-8 inches of settlement has occurred over the last 24 hours and temperatures have ranged between 17F to 25F at 7000 ft. and it is currently 17F. Winds this morning at tree line were estimated at around 30 mph from the W, and 20 mph from the WSW below tree line. On the upper mountain winds are estimated this morning at 40 mph from the W. Castle/Mt. Eddy - Mt. Eddy received 10 inches of new snow in the last 24 hours. We estimate that Castle Lake received 8-10 inches of new snow over the last 24 hours and a storm total of 5-7 feet. We estimate around 5.5 ft. of snow on the ground and a temperature at Castle Lake this morning of 18F. Weather Forecast: While the front remains in southern California, the trough continues to push cool air and snow showers into much of the State. Snow showers will continue today with a NW jet bringing strong winds to the upper mountain late tonight into Monday morning. We will have a break on Monday with a warm front arriving late Monday/Tuesday morning bringing 8-12 inches of snow on Tuesday. Although it is a warm storm, trapped cool air may keep the snow level around town (3-4000 ft.). Unsettled weather will continue through the week with high pressure developing next weekend pushing storms north of our area. For today, we can expect snow showers with 3-5 inches possible at mid elevations with some snow fall down to 1500 ft this evening. Winds today below tree line will be 15-25 mph from the SW and 20-30 mph from the WSW above tree line. On the upper mountain today, winds will be 40-55 mph from the W, moving to the NW late tonight and increasing to 75+ mph. Today expect a wind chill of -44F near the summit. Snow Pack: Skiers, snowboarders and snowmobilers enjoyed powder all day yesterday, staying mostly in the top 1-2 feet of recent snow. As we studied the snow yesterday at 7000 feet on a NE aspect, we found easy to moderate failures on several different layers in the top 2 feet of snow. What did look good in the snow pack was an increasing density and hardness ( right side up) as we went deeper into the new snow. The Rutschblock stability test showed moderate instability with failures on 2 different layers on the first jump (R4). These were 1 and 1.5 feet below the surface and we estimate that these would fail more easily on steeper slopes. For safety, we did our tests on a 23 degree slope. One of my biggest concerns over the next 24 hours will be with the strong NW winds which will develop above tree line late tonight and early tomorrow, adding to wind slabs which already exist on NE/E and SE aspects. The snow pack is still adjusting to its' new load and human triggered avalanches will be possible in steep and wind loaded terrain and you should be increasingly cautious near these areas (N/E and S aspects)! 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!