Good morning, this is Sue Burak with the Inyo National Forests Eastern
   Sierra Avalanche Center with an advisory posted on Sunday, May 11,
   2008.

   This is the last call for letters of support. For those of you from out
   of the area who use this service; let me know if you find it valuable
   for your trip planning. For locals and some of our business supporters
   and employees who use the advisories, a few minutes of your time will
   go a long way in keeping this service going.

   MOUNTAIN WEATHER

   For today, the main weather story will be the winds. A dry cold front
   will push through our area by late afternoon with warm air ahead of the
   front possibly bringing a few degrees of warming. Winds at the top of
   Mammoth are steady at about 45 mph this morning. Later today the winds
   will pick up along the 395 corridor with gusts to 30 mph. Above 10,000
   ft, moderate west winds in the 20 to 30 mph range will be accompanied
   with gusts over 55 mph.

   High temperatures at the 10,000 ft elevations in the Tioga Pass and
   Virginia Lakes areas will be in the low to mid 50s, while the southern
   Sierra around South Lake will be in the low 40s with cooler night time
   temperatures in the mid 20s.

   By Monday, temperatures will drop 6-10 degrees as the front passes over
   the eastern Sierra. By Wednesday, a large ridge of high pressure both
   at the surface and aloft will build into northern California.

   SNOWPACK AND AVALANCHE DISCUSSION

   Over the last few days, lows have been creeping up into the mid 30s.
   This morning, the low was 39 at the 9,600 ft elevation at Leavitt Lake,
   31 F at 10,000 ft on Tioga Pass and 32 on the 10,700 ft elevation at
   Gem Pass. These are the warmest low temperatures for the year at the
   higher elevations.

   With lousy overnight refreezing, the safe window of skiing and riding
   is narrow today. The daily melt freeze cycle is strongly affected by
   cloud cover and warm air masses that do not allow the snowpack to
   refreeze. Freezing allows strength recovery with surface crust
   formation. The competing forces swing back & forth like a pendulum:
   frozen solid to slushy & mushy, bomb proof to natural wet avalanches.

   With Sonora Pass open, many people are enjoying skiing, riding and
   snowmobiling. Wet slides are triggered by solar energy and skiers, but
   high marking snowmobiles make great triggers also. 13 out of 32 US
   avalanche fatalities this season were riding snowmobiles when they
   died.

   Before this morning, the snow in higher elevation terrain around Tioga
   Pass, South Lake, Bishop Pass and Charlotte Lake was freezing hard at
   night. Though the snow was soft by 1 -2 PM, there were only a couple of
   small sluffs yesterday in the South Lake area around Mt Thompson. There
   is more sluff activity in the Tioga Pass area. After one observer
   reported firm snow on the east side of Gaylor Peak and good skiing
   around 10AM, later in the day a party triggered a slide on a long
   traverse after entering a steep gully.

   For today, the avalanche danger rating is LOW in the morning,
   increasing to MODERATE on steep slopes above 35 degrees. There have
   been numerous smaller wet sluffs observed over the last week.

   BOTTOM LINE

   For today, the avalanche danger rating is LOW in the morning,
   increasing to MODERATE on steep slopes above 35 degrees. There have
   been numerous smaller wet sluffs observed over the last week.

   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.