Good morning, this is Sue Burak with the Eastern Sierra Avalanche Center with an avalanche advisory posted for Wednesday, January 16, 2008. MOUNTAIN WEATHER After a couple of spectacular mild mid winter days, the north wind returns to ridgetops and the 395 corridor. Daytime highs will be 5-8F colder today with highs at 9,000 to 10,000 ft elevations seeing highs in the mid 30s. North winds will be in the 10-20 mph range with gusts up to 60 mph. Above 10,000 ft, highs might reach 28F with north winds 20 to 30 mph with gust to 70 mph. Night time lows will be in the 13-17 F with lower temperatures in the Crowley Lake and Lee Vining areas. There is a hazardous weather statement posted for the Owens Valley and the eastern slopes of the Sierra for gusty north winds today. After the disturbance moves through, temperatures will gradually warm until Saturday or Sunday, when a cold front drops down from Alaska and brings a chance of upslope showers. SNOWPACK AND AVALANCHE DISCUSSION Mild winter days and cold nights are the perfect recipe for surface hoar and near surface faceting. On southern aspects above 9,000 ft, small faceted grains were visible on the snow surface. In small pockets where the wind had missed hammering the snow, near surface facets comprised the upper 1-2 inches of the snow surface. Surface hoar has been forming and if you take a chunk of the abundant crusts at all elevations, you will see facets under the crusts. The snowpack has stabilized on all aspects over the last three to five days. Snowpack stability tests show some weakness in the upper 20-30 cm with several wind layers from last week's storms still showing up with moderate test results. My extended column tests are showing little, if any, propagation compared to compression tests which show a few easy and alot of moderate results. Firm to hard wind board is found in alpine terrain on all aspects. Tree skiing has some dense settled powder along with a variety pack of thin to thick suncrusts and melt freeze crusts. Lots of steep, exposed lines are being skied with no reports of skier triggered slides, though wind stripping has resulted in a shallow pack with less than desirable coverage. Though it's not powder, skiing and riding conditions are pretty good above treeline. With a little more solar radiation reaching south, west and east aspects below 9,500 ft, rollers, sunballs and wet point release slides are telling us the snow surface has been unstable mid day. The snow on these slopes will become frozen death cookies the next two days with cold temperatures and moderate north winds. BOTTOM LINE Most terrain has a LOW avalanche danger, though there continues to be isolated pockets of the MODERATE danger rating for steep, rocky terrain with a thin snowpack. Recall that when depth hoar or faceted snow collapses, fractures like to propagate from rock to rock or tree to rock- the so called islands of safety. Consider the consequences of being caught in a slide- what chance do you have of hitting rocks or trees? Will it be a shallow or deep burial? Please note that the avalanche danger rating in this advisory expires in 24 hours. This advisory is our best interpretation of snow pack conditions and NWS forecasts issued today. Backcountry travelers should be aware that elevation and geographic distinctions are approximate and that a transition zone exists between upper and lower elevations. Avalanches do not happen by accident and most human involvement is a matter of choice not chance. Most avalanche accidents are caused by slab avalanches that are triggered by the victim of member of the victim's party. Even small slides can be dangerous. Always practice route finding skills and carry avalanche rescue gear. Remember that avalanche danger ratings are only general guidelines. Distinctions between geographic areas, elevations, slope aspects and slope angles should be made.