Good morning, this is Sue Burak with the Eastern Sierra Avalanche
   Center with an avalanche advisory posted for Wednesday March 12, 2008.

   MOUNTAIN WEATHER

   As the weekend approaches, the probability for snowfall increases.
   Morning skies are cloudy with temperatures around 32 F from Bishop to
   Lake Sabrina, Rock Creek and Mammoth. This is quite different from
   yesterdays forecast for sunny skies today. Winds area calm this morning
   but are expected to increase later today as a large and impressive cold
   system impacts our area from Thursday through Sunday. The west coast
   ridge flattens today and Thursday in response to the approaching storm.

   West winds will be picking up today especially at elevations above
   9,000 ft., with gusts up to 50 mph expected on the ridgetops. Below
   9,000 ft. winds will be from the southwest with gusts up to 20 mph.
   There is a High Wind Watch posted for the Owens Valley and southern
   Sierra beginning at noon on Thursday.

   Higher elevations are forecasted to be about 5-10 degrees F today.
   Highs at 9,000ft are expected to be around 40F after highs in the low
   50s yesterday with higher elevation temperatures pulling back into the
   upper 30s. Elevations above 10,000 ft will see high temperatures in the
   upper 30s with west winds increasing by late in the day.

   Low temperatures should begin to fall from near freezing to the mid
   20s. By the weekend, lows will be around 10-15F with highs near 20F.

   By the weekend, winds become more southwesterly which favors orographic
   snows. Jet stream levels are quite cold with this storm (-22 F to -31
   F) and snowfall could be heavy in isolated areas similar to summer
   thunderstorms. At this point, it looks like the southern Sierra will
   see only scattered snow showers with alot of wind. Snowfall amounts
   from Mammoth northward look to be on the lighter side, though things
   could change quickly as the storm approaches and forecasters get a
   better idea of how much snow will fall.

   SNOWPACK AND AVALANCHE DISCUSSION

   Spring snow conditions are found on east to west aspects below about
   10,500ft, depending on whether one is traveling north or south of
   Mammoth and Rock Creek. The sun exposed slopes at higher elevations can
   be spring snow or frozen crust depending on slight changes in aspects.
   There are two crusts in the upper 15 cm of the pack at the elevations I
   have been traveling through. The surface melt freeze crust is strong
   when frozen. Below this crust are several inches of moist winter snow
   which is lying on top of another very strong and thick ice layer.

   Over the last 5 days, temperatures at the 9,000 ft elevations and above
   have been in the 40 to 50 F range. Solar radiation is maxing out at
   high elevations at over 1000 watts per square meter. Once the winds
   calmed down the last few days, radiation energy has determined what
   goes on at the snow surface. Even though the snow is becoming mushy in
   the afternoon, there has not been a lot of wet slide activity, despite
   some locations having only an hour or so of freezing temperatures at
   night. The crusts are thick and strong and need a few more days of
   intense solar energy, light winds and temperatures in the low 50s
   before there will be a wet slide avalanche cycle.

   With the spring weather coming to an end by today or tomorrow, we will
   have to wait until next week for the wet snow cycle to begin all over
   again.

   For today, the main stability concern continues to be smaller wet snow
   avalanches resulting from solar radiation. If cloudy skies persist
   through the day, the clouds emit longwave radiation which adds energy
   to the snow. Most elevations did not get a solid freeze last night and
   this mornings cloud cover could result in soft snow conditions this
   morning. If the surface mush gets deeper than 6-8 inches or you start
   breaking through the surface crust, its time to head to another less
   sun exposed aspect.

   BOTTOM LINE

   The avalanche danger is LOW today, with a MODERATE danger on 35-40
   degree slopes receiving intense solar radiation. If cloud cover
   continues, the MODERATE danger rating applies to all steep slopes and
   aspects above 9,5000 ft.

   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.