Avalanche Advisory for Wednesday, December 27, 2007 at 6:45 am By Eric White & Nick Meyers 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 89% of normal. We currently have around 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 above normal precipitation into the spring of 2008. Weather Observations: We have high clouds and cool temperatures this morning. Mt. Shasta - We have 33 inches of snow on the ground near tree line with only a trace to 1 inch of new snow over the last 24 hours. The snow settled 2 inches in the last 24 hours and temperatures have ranged between 11F and 17F at 7000 ft. and it is currently 11F. Winds this morning at tree line were estimated at around 25-30 mph from the NW, and light and variable below tree line. On the upper mountain winds are estimated this morning at 75 mph from the NW. Castle/Mt. Eddy - Mt. Eddy received only a trace to 1 inch of new snow in the last 24 hours with 2 inches of settlement. Temperatures stayed cool between 10F to 21F over the last 24 hours. We estimate around 2 ft. of snow on the ground with brush showing. Castle Lake is around 7F this morning. Weather Forecast: A good looking storm is just now hitting Washington and Oregon and lurking off our coast this morning. It will arrive later this morning but the orographics aren't favorable for Mt. Shasta. However some areas in the Siskiyous and coast range will get more snow and rain. Another small storm will arrive on Friday with a warming and drying trend into early next week. For today we can expect increasing clouds with snow beginning this morning. The snow level will start off fairly low (1000 - 1500 ft.) then rise up to around 3000 ft. with 3-5 inches possible by tomorrow morning. Temperatures at mid elevations will warm into the teens (14-18F). Winds below tree line will be 5-15 mph from the SW and increase tonight to 20-25 mph. At and above tree line, winds will be 25-35 mph from the NW and increase this afternoon up to 55 mph from the NW, then decrease tonight to 35 mph from the WNW. On the upper mountain winds will be up to 80 mph this morning from the NW, then decrease to 60 mph this afternoon and increase tonight to 70 mph from the NW. Snow Pack: With warming temperatures last weekend and cold temperatures over the last few days, we have very hard snow in open areas and a breakable crust in the trees with a dusting of new snow. Yesterday, Nick and I identified future problems with the surface crust. We found large graupel (ball bearing snow) on top of the crust and facets underneath it, with fairly easy failures during stability tests. Forest Service Ranger examing the snow 12/26/07. Nick examines the crust 12/26/07 after easy failures. While this is not a concern this morning, it will become a concern with snowfall and wind loading later today and tomorrow. While the forecast snow fall doesn't look like that much, wind loading could create 2-3 ft wind slabs on southerly and easterly aspects. Be observant today and avoid recently wind loaded slopes greater than 30 degrees. 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!