Good morning, this is Sue Burak with the Eastern Sierra Avalanche
   Center snow and weather update for Sunday December 23, 2007.

   MOUNTAIN WEATHER
   Todays temperatures reached the low 40s in mountain locations above
   9,000 ft. The high temperature at Main Lodge was 41 F today, the
   warmest daytime temperature in at least 10 days.

   Cloud cover will prevent lows tonight from reaching the single digits
   with lows in the 20s expected at most mountain elevations. Today will
   be mostly cloudy with northwest winds 10-20 mph with gusts to 35 mph
   and highs in the mid 30s. Above 10,000 ft, expect north winds at 20-30
   mph with gusts to 45 mph. Highs at the higher elevations will cool off
   from near 40 to 28-36 F.

   Another storm is passing to the north tonight and tomorrow. The
   Christmas night and Wednesday storm is headed north also.

   OUTLOOK

   The only thing long range models agree on is a return to colder
   temperatures by middle of next week. Longer range fantasy models show
   a stormy period the first week of January but this is like reading tea
   leaves.

   SNOWPACK AND AVALANCHE DISCUSSION
   The new snow resulted in a flurry of skiing activity over the last few
   days, mainly in the Mammoth Lakes Basin. In general, skiing conditions
   are good in bowls but rocks and tree obstacles are numerous. The lower
   third of the Sherwins is mostly bushwhacking.

   Snowpack structure from a number of observers and my pit work shows a
   depth hoar basal layer of 1-8 inches. A compression test in the Tele
   Bowls failed on CT4 20 cm down with failure of the entire 60 cm block
   at CT 7. Other tests show a distinct inter storm or wind direction
   change layer at about 30-40 cm down. Compression test failures on this
   layer range from easy to moderate.

   Compared to last year at this time, the Mammoth Lakes has about 2-3
   feet of snow compared to 2 feet from last year. Rock Creek, Bishop
   Pass and Tioga Pass have about 30 % more snow depth than last year at
   this time.

   Slide Canyon has about 6 inches more snow; Leavitt Lake has 5 inches
   less snow than last year at this time. Tioga Pass has the same amount
   of snow as last year.

   Last year, the grim year, Mammoth Pass had 3.4 of water content. This
   year on December 22, there is 7.6 of water, about double from last
   year at this time.

   Farther south, Rock Creek (9600 ft) has 8 inches more snow and 2
   inches more water than last year at this time. Bishop Pass at 11,400
   feet has the same amount of snow on the ground as last December, with
   more water this year. To really put things into perspective, in a
   normal or average year of precipitation, there would be at least
   double to three times the amount of snow on the ground.

   BOTTOM LINE
   Avalanche danger ratings will resume when more snowfall comes.

   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.