Good morning, this is Sue Burak with the Eastern Sierra Avalanche Center with an avalanche advisory posted on January 22, 2008. The beacon basin training facility at the USFS is now operational. Many thanks to the hardy folks who dug trenches in hard snow and spliced wires in the cold and dark to get the facility running! MOUNTAIN WEATHER We have plenty of cold but little new snowfall. Reno and Carson City received over 6 of snow yesterday while Mammoth picked up a couple of inches of fluff. The Central Sierra Snow Lab on Donner Summit picked up 10 of new snow. Expect scattered snow showers this morning followed by clearing mid day to early afternoon. Tuesday night could be clear and cold. Snow showers will increase Wednesday as the low opens up and moves to the east. The main precipitation band could be over southern Mono and all of Inyo County. The Hanford office is calling for heavy rain in the Central Valley Wednesday night. At mid elevations from 8,000 to 10,000 feet, winds will be from the south over the next few days. Higher elevations could see east winds gusting to over 40 mph. By Thursday, a second closed low slides down the West coast and parks itself in the same position as the current low, right off San Francisco Bay. Models indicate this low could pick up subtropical moisture and, if it behaves as the NAM time height sections suggest, Mono County could see significant snowfall Thursday afternoon into Friday morning. This all sounds good on paper, but there are timing and precipitation amount discrepancies between models and Las Vegas, Reno and Hanford NWS offices. Farther out, the Reno NWS office sees the potential for a real Sierra storm for the Sunday- Monday period. However, Hanford NWS does not mention this event. As advertised, temperatures fell Sunday afternoon and highs on Monday were in the low 20s from Cottonwood Lakes to Virginia Lakes. For today through Friday, the cold weather will continue with highs in the upper teens at the 8,000 to 10,000 ft elevations and cold nights around from -5F to + 5F. Lee Vining, Crowley Lake and Toms Place will see highs in the upper 20s and single digit lows. The Owens Valley will be the hot spot with highs in the low 40s. The La Nina is strengthening and is forecasted to remain strong over the next two months and into the spring. Sea surface temperatures are -2C below average temperatures which indicates a very strong La Nina event. Long range climatological forecasts call for dry conditions through the end of the winter. Lets hope the forecasts are wrong. SNOWPACK AND AVALANCHE DISCUSSION Strong winds Sunday afternoon and Monday moved some snow onto NE and eastern aspects at the higher elevations. Recent wind slabs may be poorly bonded to firm windboard surfaces as well as areas that had near surface faceted grains before the clouds came in on Sunday. You can find these faceted surface grains in openings in mid to high elevation glades and especially in areas south of Mammoth. In areas with suncrusts, there are large facets under the crusts. This could be a source of instability with rapid loading from new snowfall. The snowpack south of Mammoth is much different from the Sherwins (except Tele Bowls) and the Mammoth Lakes Basin. This is due mainly to a much shallower snowpack- more faceted snow is found throughout the pack south of Mammoth. Shallow areas around and along ridgetops have little cohesion and booting up can be a wallow. However, compression and extended column tests are giving Q2s and Q3s with no compression collapses on the ground. The main avalanche concern in all areas is recent windloading. Even though only a few inches of snow have fallen at the ski area study plot, the wind can take that snow and multiply several times over to create wind slabs. Pay attention to wind direction the next few days. Winds could be from the south and east so loading patterns will be different than the usual southwest wind loading patterns. BOTTOM LINE For today, the avalanche danger is LOW with isolated pockets of MODERATE danger on north to east aspects. If winds shift to the east at elevations above 10500 feet, look out for loading on west facing slopes. 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.