Avalanche Advisory for Thursday, January 3, 2008 at 6:45 am By Eric White Special Note: The Avalanche Danger is expected to increase with strong winds and heavy snow fall from Thursday, January 3 through Sunday, January 6. A blizzard warning has been posted by the NWS for Mt. Shasta from 10am today through 10pm Saturday night. Avalanche Watch posted for 1/3/08 to 1/6/08. We are expecting increasing avalanche danger for both natural and human triggered avalanches above 5000 feet over the next 72 hours. Stay off of, and out from underneath, slopes steeper than 30 degrees. 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 82% of normal since September 1. We currently have around 2-3 feet of snow below tree line and from 0-6 feet of snow above tree line. 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 overcast skies this morning with a temperature in town of 38F and gusty SE winds. Mt. Shasta - We have 33 inches of snow on the ground near tree line with no new snow over the last 96 hours. No settlement was observed over the last 24 hours and temperatures have ranged between 28F to 37F at 7000 ft. and it is currently 28F. Winds this morning at tree line were estimated at around 55 mph from the SSW, and 15-20 mph from the S below tree line. On the upper mountain winds are estimated this morning at 50+ mph from the SW. Castle/Mt. Eddy - Mt. Eddy received no new snow in the last 96 hours. We estimate around 2 ft. of snow on the ground with brush showing. Weather Forecast: A powerful series of storms will move through our area over the next few days and a Blizzard Warning has been posted from this morning through Saturday night. A strong low pressure trough from the Gulf of Alaska will bring several feet of snow and strong winds, beginning to pick up this afternoon and again tomorrow morning, continuing through the weekend. The heaviest precipitation will be from this afternoon through Friday afternoon. The snow level will fluctuate around 3500-4500 ft., then drop to 1500 to 2500 ft. Saturday. There will be good orographics for Mt. Shasta, Castle Lake and portions of the Trinities. The central Sierra will get an added boost of moisture from the south and receive more snow than the north state. For today we can expect snow beginning later this morning with 1.5 to 2 feet accumulating by tomorrow morning. Winds below tree line will be from the SSW at 20-30 mph and S gusts to 55 mph tonight. Above tree line and on the summit winds will increase to 70-80 mph from the SW and WSW over the next 24 hours. Temperatures today at mid elevations will be in the mid 20's to low 30's. Snow Pack: The pre-storm snow pack has been showing good stability, but several weak layers exist near the surface which will add to the instability expected with the blizzard conditions. Heavy snow fall and strong winds (2 of the classic red flags of avalanche danger) will stress the snow pack and natural avalanches will be possible tonight and into the next few days. We expect avalanches to occur mostly in the new storm snow with both soft slabs and wind slabs. Safe route finding will be important over the next few days as well as avoiding slopes steeper than 30 degrees and keeping far away from cornices. Remember, the access roads to Castle Lake and Bunny Flat are not plowed on a regular schedule and may be closed and remain unplowed for a few days during large winter storms. Climbers should wait for better weather and safer avalanche conditions before attempting to climb Mt. Shasta. 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!