[C:%5CDOCUME%7E1%5Cmhill%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_im age002.jpg] The Mt. Shasta Avalanche Center Avalanche Advisory for Tuesday, December 18, 2007 at 3:00am By Eric White The next Avalanche Advisory will be posted: 12/19/07 The Bottom Line: Avalanche Danger Rating for today: Trend: Extreme Widespread natural or human triggered avalanches are certain High Natural and human triggered avalanches are likely. X Considerable Natural avalanches are possible and human triggered avalanches are probable. Moderate Natural avalanches are unlikely. Human triggered avalanches are possible. Low Natural avalanches are very unlikely. Human triggered avalanches are unlikely. Avalanche Danger is expected to Increase X Avalanche Danger is expected to continue at this rating Avalanche Danger is expected to Decrease Where? Above 6000 ft on Easterly and Northerly aspects greater than 35 degrees on Mt. Shasta. Above 5500 feet on northerly aspects in the Castle/Eddy area. Size and Character: Medium sized slabs below tree line and medium hard slabs (wind slabs) which will travel to tree line. Sensitivity to Triggering: These will be triggered by an individual or group. Level of Uncertainty: Low Moderate High --- The Details: This Season: We had a few early season hints, then a dry spell with December starting to show signs of winter. Our precipitation is around 80% of normal and we may catch up over the next few days. We are in a "La Nina" climate condition which often means wetter than normal winters in our area. Weather Observations: We currently have limited remote weather station data. Mt. Shasta - We currently have 38 inches of snow on the ground near tree line with around 17 inches over the last 24 hours. In the last 24 hours temperatures have ranged between 28F to 25F at 7000 ft. We have a storm total of 24 inches of new snow and around 3 inches of water content. Winds this morning above tree line were estimated at around 60 mph from the SW, and around 25 mph below tree line from the S. Castle/Mt. Eddy - Mt. Eddy received around a foot of new snow while Castle Lake was closer to 18 inches over the last 24 hours. Temperatures were between 24F to 29F over the last 24 hours. Weather Forecast: Another decent winter storm will arrive early Wednesday morning and continue most of the day brining another 10+ inches of snow. The snow level will fluctuate around town (3500ft.) and then drop well below town into Thursday morning. We have moved into a good weather pattern and storms and short dry periods will continue through the weekend. Winds are expected to increase Wednesday to 50mph from the S/SW above tree line and up to 80mph near the summit. Snow Pack: Before this storm series we had variable conditions with powder, breakable crust and HARD snow in windy areas. The shallow snow pack and cool temps over the last 2 weeks have created a lot of facets (a good weak layer) and the first snows of this storm cycle came in cold and didn't bond well to the hard snow. Snowfall became heavy this morning with 2-3 inches/hour and became pretty heavy. Natural avalanches were reported with one out of bounds near the Ski Park which was 2 ft. deep and 250 ft. wide and piled up deeply on a NE aspect and around 7000ft. I expect things to get more exciting tomorrow with the forecast winds and snowfall. Many people are excited for the beginning of winter recreation, but, don't let that blind you to the sensitive conditions we are expecting. Avoid recently wind loaded slopes greater than 30 degrees. Continue to watch for shallowly buried rocks, sticks and logs. 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! Please give us comments on our new format and report weather and snow observations: (530)926-9614 Thanks! Some things to consider: Backcountry travelers should make terrain, weather and snow pack evaluations as they travel over snow covered terrain. Remember that seemingly insignificant slides may be dangerous. Almost half of all avalanche fatalities occur in slides traveling less than 300 feet. Fall Season Watch Outs! * Surface sluffs and wind slabs * Shallowly buried rocks and trees can cause serious damage or injury. * Sink holes around brush and small trees can be dangerous. * Snow bridges over crevasses can be touchy and unsupportable. * Shallow snowpack with cold air temperatures can produce unstable snow These are just a few things you should watch out for when traveling during the early part of the winter season. The Five Red Flags of Avalanche Danger any time of year include: 1) Recent/current avalanche activity 2) Whumpfing sounds or shooting cracks 3) Recent/current heavy snowfall 4) Strong winds transporting snow 5) Rapid warming or rain on snow.