Good morning, this is Sue Burak with the Eastern Sierra Avalanche
   Center with an avalanche advisory posted for Sunday, January 13, 2008.

   MOUNTAIN WEATHER
   After a long week of snowy and unsettled weather, we should see clear
   skies today as a high pressure ridge builds over the West Coast.

   Daytime temperatures will continue to be mild for this time of year
   with highs in the low to mid 40s at the 9,000 ft elevation. Elevations
   of 10,000 feet and higher will see highs in the mid to upper 30s. Lows
   will be around 20 F at the higher elevations and in the mid to upper
   20s at the 9,000 ft elevations. Winds will be from north and northwest
   today in the 10-20 mph range above 9,000 ft. Windy weather is
   forecasted for Monday night through Tuesday.

   Highs on Saturday reached 47 at Mammoth Pass, 41 at Main Lodge, 36F at
   Tioga Pass, 35F on the Tyndall Plateau and 59F in Bishop.

   The shift in wind directions last night from the southwest to
   northwest and north signal a building ridge of high pressure over the
   West Coast. The 10 day forecast is for clear skies with no
   precipitation.

   SNOWPACK AND AVALANCHE DISCUSSION
   Temperature plots of the last 10 days from various east side recording
   stations show the same story- there has been a gradual upward trend in
   daytime highs with nighttime temperatures generally remaining in the
   mid 20s. Even Mt. Warren, at 12,300 ft, has seen daytime highs rise
   from around 2F earlier in the week, to 24 F on Saturday.

   Warming temperatures, windy conditions, high relative humidity and
   some rain the last few days have added energy to the snowpack. The
   results are rain crusts and increasing snowpack stability along with a
   decline in skiing and riding conditions. Some surface melt has also
   occurred on south and west aspects between 8,000 and 10,000 feet,
   creating thin to thick crusts on top of rain crusts.. Weak facets near
   the ground where the snowpack is greater than about 50 inches are
   buried more deeply than in shallow areas and are harder to get to fail
   than earlier in the week.

   There is a wide range of snow conditions in the forecast area. An
   observer skiing the grand loop off the backside of Mammoth to Reds and
   back to Tamarack reported settled powder in the trees with soft
   breakable crust in open areas. Another observer in the recently opened
   Rock Creek drainage reported large sunballs on east to northeast
   aspects between 8,700 to 9,300 ft. Sunballs are a sign of surface
   instability. Sunballs were reported from the 9,000 ft elevation in the
   Bardinis. This party found heavy snow in the trees and a 4 thick
   faceted layer at the ground. An easy shear was reported 16 inches down
   with a second weak layer on the ground.

   South on Kid Mountain, observers reported a snow depth of 61 inches in
   a wind loaded area at 9,000 feet. Skinning proved to be a bit
   challenging due to firm wind-blown snow. Skiing was generally good,
   though a bit variable - pockets and patches of powder surrounded by a
   bunch of wind board. They found 8 inches of large facets on the
   ground. In a nearby pit in a shallow (24 inches) area in the main
   gully on the north face of Kid Mountain, the facet layer collapsed as
   the column was isolated. The wind board layer was 6-7 inches thick and
   failed easily where the wind board was sitting on top of lower density
   snow. They also found weakness within a storm layer.

   Results from the upper reaches of the Mammoth Lakes Basin were
   somewhat similar with a faceted layer on the ground at 11,000 feet.
   However, this faceted layer has gained strength this week and I was
   not able to get any collapse of the layer. In wind loaded areas, there
   was easy shears in compression tests at 16-18 inches down from the
   surface, but fractures did not propagate in the extended column test.

   Finally, strong northwest winds were moving a lot of snow onto
   southeast aspects on Pointless Peak. Farther north in the Tioga Pass
   area, winds at Ellery Lake are gusting to 40 mph from the southeast
   and winds on Mt Warren are ripping from the northwest at 40-70 mph.
   This is a heads up that wind loading is possible on the usual northern
   aspects as well as on east to south facing slopes.

   BOTTOM LINE
   For today, the avalanche danger rating is MODERATE on north to south
   facing slopes greater than 35 degrees. The MODERATE danger rating
   means natural avalanches are unlikely but human triggered avalanches
   are possible in recently wind loaded steep north to south slopes above
   treeline. Also pay attention to sunballs and rollers on steep sun
   exposed slopes with increased solar radiation. A soggy point release
   avalanche could knock you off your feet.

   Please note that this danger rating expires Tuesday evening at 6 PM.
   This advisory is our best interpretation of snow pack conditions and
   NWS forecasts issued today. This is a regional forecast and
   significant variations may exist within the forecast area.

   The information and danger ratings are intended as a trip planning aid
   for recreational, backcountry users of avalanche terrain; they are not
   meant to be used as the sole factor in determining the avalanche
   danger presented by a specific slope.

   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 or 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.