Good morning, this is Sue Burak with the Inyo National Forest Eastern
   Sierra Avalanche Center with an avalanche advisory for Friday, February
   6, 2009.

   MOUNTAIN WEATHER

   A winter storm warning is in effect from 7AM today to 4 AM Saturday for
   the east slopes of the southern Sierra. The best chance for snowfall
   will be this afternoon into Friday evening, with 12 to 22 inches of new
   snow possible above 10,000 ft. Lower elevations in the southern Sierra
   could see 10 to 18 inches above 5,500 ft. The position of the low
   pressure system is off the central and southern California coast and a
   piece of energy started moving east last night. The main period of
   snowfall will be from about 3 PM through midnight. The White Mountains
   and central Nevada could get more snow than Mono County due to the path
   the storm is taking as it moves east.

   For Mono County, there is a winter weather advisory posted for Mono
   County for today. Widespread snow will fall this afternoon through
   tonight with snowfall accumulations hopefully in the 8-15 inch range
   between 8,000 and 9,000 ft. Higher elevations could see snowfall
   accumulations by Saturday morning in the 10 to 21 inch range. This weak
   system has little jet stream support and winds will be light and mainly
   from the southerly direction. High elevation windspeeds will be in the
   20-30 mph range with gusts around 45-60 mph. As the low moves east,
   winds will come from the north and northwest but will continue to be
   light.

   With cloud cover, lows this morning are in the mid 20F range. Daytime
   highs will be in the 20s at 8,000 to 9,000 ft. Higher elevations will
   see high temperatures in the upper teens to low 20s.

   SNOWPACK AND AVALANCHE DISCUSSION

   For those of us who love to ski and ride in the southern Sierra, please
   be advised that east side locations from 8,000 to 12,000 ft had 0 to 20
   inches of snow on the ground prior to this storm.

   Yesterdays storm dropped about 4-5 inches of new snow in the Mammoth
   Lakes basin. Observers report light winds in the Basin and 8% new snow.
   Over 9 inches of new snow fell on the ski patrol study plot on Mammoth
   Mountain. June Mountain reported 6 inches of new snow in the parking
   lot early this morning. Areas north and south of Mammoth and June
   Mountain received only an inch or two of new snow.

   Over the last week, clear days and cold clear nights created perfect
   conditions for wedge like surface hoar formation. Large surface hoar
   grew all day, even in the sun on north facing terrain. In the trees,
   surface hoar grew in open areas between trees. In these open areas in
   glades, surface hoar grew on fragile, thin suncrusts. Watch for it in
   open meadows in the Lakes Basin and the June Mountain region. Avoid
   climbing steep open slopes in the trees, especially convex shaped
   slopes. Pockets of surface hoar could be lurking in shallow depressions
   and the sides of gullies and chutes in high terrain. To make stability
   evaluations even trickier, it is not a widespread and uniform layer in
   the Sierra. It can be found in one place but not another.

   With more snowfall expected later today and through the night, surface
   hoar, small faceted snow grains and fragile sun and wind crusts will be
   buried under new snowfall. This buried weak layer will become the
   avalanche concern for later today and Saturday and Sunday.

   The other avalanche concern is wind loading. Despite light winds, winds
   are still strong enough to transport snow and create trigger-sensitive
   soft wind slabs. Newly formed wind slabs will be found right off the
   top of exposed north facing slopes that are steeper than 35 degrees.

   BOTTOM LINE

   For today the avalanche danger is estimated to be Moderate on east and
   north slopes above 8,000 ft. The MODERATE danger rating means there are
   locally unsafe conditions. Evaluate each slope and the type of terrain
   carefully. Use good travel habits to minimize risk. The avalanche
   danger is expected to increase today as the next storm moves into the
   area.

   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.