Good morning, this is Sue Burak with the Inyo National Forest Eastern
   Sierra Avalanche with the avalanche advisory for Thursday, March 5,
   2009.

   MOUNTAIN WEATHER

   We will see mostly sunny skies and calmer winds today. Scattered snow
   showers will occur over the highest terrain along the Sierra Crest and
   temperatures will be cold with highs in the middle teens. Southwest
   winds will gust up to 30 mph. Daytime temperatures will be a little
   warmer at middle elevations with highs close to 30 F at the 8,000 to
   9,000 ft elevations.

   West winds will pick up Friday along with a chance for snow showers.
   Weekend storms should affect far northern areas. The longer range
   outlook is dry.

   SNOWPACK AND AVALANCHE DISCUSSION

   After a very windy weekend, Sunday nights storm came in with rain and
   high snow levels. Up to 2 inches of water came with 8 to 14 inches of
   new snow. The resulting layer resembles the end of January lens with a
   slippery sliding surface and small faceted snow forming above and below
   the layer. New dense snow quickly formed a cohesive slab and control
   work on June Mountain released many 1 to 2 foot slab avalanches.
   Graupel was found in and above this storm snow and is a potential weak
   layer within the storm snow, especially above the March 2 rain/snow
   lens. Graupel does not fragment and pack as easily as other snow grains
   and will keep its rounded form for up to a week when buried.

   Snowfall on Tuesday and yesterday was accompanied by relentless
   southwest winds screaming along with 100 mph plus gusts recorded on the
   top of Mammoth Mountain and Mt. Warren. Exposed wind prone areas like
   Ellery Lake and Lake Sabrina got hammered by gusts over 50 and 60 mph.
   It is hard to imagine the amount of snow that was blown onto north and
   east facing terrain in the trees and above treeline. The subtropical
   influence of the storms and southerly flow kept snow densities well
   above 10%.

   The primary avalanche concern today is wind loading. Yesterdays
   snowpack tests in Rock Creek released cleanly and easily on graupel and
   on the recent rain layer of March 2. Both north and west slopes were
   tested with similar results. The higher elevations of Rock Creek
   received only a foot of new snow compared to the 3 to 4 feet received
   in locations around and north of Mammoth. Natural avalanches are
   possible today and human triggered avalanches are probable. Give
   yourself a little more margin for error than you normally might, use
   routes, travel techniques, and group management practices that minimize
   the time people are exposed to potentially unstable slopes.

   The secondary avalanche concern is the recently buried rain/snow layer
   resulting from the wet snow that fell Sunday night and Monday. This
   layer has faceted snow grains above and below the layer. There are also
   deeper buried layers but the recent layer has the greatest potential
   for skier triggering.

   BOTTOM LINE

   For today, easily triggered, widespread wind slabs are likely on all
   north to east facing slopes at mid to high elevations. Exposed open
   areas in the trees are likely to have wind slabs. The avalanche danger
   rating is CONSIDERABLE in all wind loaded terrain with slope angles
   steeper than 35 degrees. The avalanche danger rating is MODERATE on all
   other aspects. Safe travel depends on paying close attention to obvious
   clues, especially whumpfing, shooting cracks and recent or current
   avalanches.

   For the Rock Creek to Bishop Creek area, there is a CONSIDERABLE danger
   rating today for all wind loaded terrain above treeline. Skier
   triggered avalanches in storm snow could step down to weak faceted snow
   above the ground. There is a MODERATE danger rating for slopes less
   than 35 degrees. It is possible a skier could trigger a slab in new
   snow that could step down to the weak faceted snow above the ground.

   Please note that the avalanche danger rating in this advisory expires
   in 24 hours. 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.