Good morning, this is Sue Burak with the Eastern Sierra Avalanche Center with an avalanche advisory posted for Sunday, March 2, 2008. MOUNTAIN WEATHER A cold front will move across the area behind the Pacific storm that brought clouds and winds to the area on Saturday. Strong northerly winds have developed as the system moves east. The Owens Valley and eastern slopes of the Sierra will continue to see strong northerly winds for much of today. Wind speeds for today vary by elevation. At the 9,000 ft elevations, light to breezy north winds in the 10-15 mph will veer to the east later in the day. Above 10,000 ft, north winds will be stronger with gusts over 45 mph for most of the day. By Monday, winds will be light until the end of the week. Daytime temperatures will remain close to normal for this time of year with highs at the 9,000 ft elevation around 40 F. Higher elevations will see highs in the low 30s. Lows will be in the low teens for Sunday and Monday night. SEASONAL WEATHER AND PRECIPITATION DISCUSSION The following information comes from the State climatologist. This La Nina is the strongest in 8 years, and in the top 1/3rd of La Ninas. Forecasts are for it to continue at least at moderate strength through April, May and June. This year has been an atypical La Nina for California with eastern Sierra snowpack totals running around 90-100% of normal for this time of year. The reason this strong La Nina year is unusual in precipitation totals is most likely due to the Madden/Julian Oscillation (MJO). MJO refers to periods of enhanced convection (storm activity) over the tropics. These fluctuations may occur every 30-60 days. For our part of the world, the MJO can promote an extension of the jet stream all the way across the Pacific to the west coast of the United States, leading to rain. This pattern can occur even during strong La Nina conditions, which primarily set up a blocking ridge over the west coast. Most La Nina high pressure domes are difficult to penetrate, more so in the second half of winter. That is why La Nina's typically bring reduced rainfall in January, February and March. But this year, there have been a couple of rounds of storms that may have been set up by this MJO. SNOWPACK AND AVALANCHE DISCUSSION Yesterdays strong winds moved snow around some areas like the north side of McGee, upper Rock Creek Canyon and Bishop Creek. Other areas with equally strong wind speeds did not show much transport. Since there is no clear distribution pattern, other than any transport occurred in north facing terrain, local slope by slope observations are essential. Where wind drifting has occurred, expect unstable slabs near ridgetops that could be reactive to light triggers. Field work and many observer reports show the snowpack is well bonded. Snow conditions range from nice creamy powder on protected north facing slopes from 9,000 to 12,000 ft. However, the winds probably ruined a lot of settled powder skiing, especially above treeline. Other aspects have 2 to 5 inch thick suncrusts which are supportable in the cold mornings but turn to aggravating punchy conditions later in the day. It is still a bit early for winter corn above 9,500 ft. South, west and east aspects are showing signs of surface instability in the form of sunballs and point release slides. With continued north winds today cooling the snow surface, the winter corn cycle may be delayed until mid week. At low to mid elevations, southerly facing slopes are in a melt freeze cycle and will be stable until turned to mush by increased solar radiation. In many places, the snow beneath the surface crust is rotten and weak to the ground The two avalanche concerns for today are wind loading in isolated pockets off steep north facing ridges and solar radiation on east, south and west aspects. Check out cornices as they are showing signs of dropping and sagging. Avoid hiking up slopes with cornices at the top. Look up and think about whats above; the valley or lower slopes may not be indicative of conditions higher up. BOTTOM LINE The avalanche danger rating today is LOW in the morning on east, south and west aspects. The avalanche danger will increase to MODERATE as solar radiation reaches maximum energy mid day. On north aspects above 9,000 ft, the avalanche danger rating today is LOW with areas of MODERATE danger in steep wind loaded terrain. 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.