Good morning, this is Sue Burak with the Inyo National Forest Eastern
   Sierra Avalanche Center with an avalanche advisory for Feb. 14, 2009.

   MOUNTAIN WEATHER

   The active weather pattern continues with leftovers from yesterdays
   system bringing low visibility to Mammoth Mountain this morning and
   cloudy skies in Mammoth. Skies are mostly clear this morning in June
   Lake and the mountains west of Bishop.

   High temperatures will be in the low to mid 20s today at the 8,000 to
   9,700 ft elevations. The ever present wind will continue from the south
   and southwest winds in the 10-20 mph range with gusts to 30 mph. The
   higher terrain above 10,000 ft will be a windy place today with
   southwest winds 25 to40 mph with 60 mph gusts. It will be cold today
   over the higher terrain with highs from 2 to 12 F.

   For tomorrow, the National Weather Service in Reno has issued a winter
   storm watch beginning Sunday afternoon through Monday afternoon.
   Snowfall totals for this system have varied over the last few days and
   the latest guess is for 1 to 2 feet of snow on Mammoth and along the
   Sierra Crest. Southwest winds will be very strong with gusts exceeding
   70 mph over the ridgetops.

   The Sunday and Monday storm is forecasted to bring subtropical moisture
   along with cold Gulf of Alaska air so a period of heavy snowfall is
   expected from Monday afternoon. This mornings NWS long range forecast
   is for clearing skies and an end to the stormy unsettled weather
   pattern by mid week.

   SNOWPACK AND AVALANCHE DISCUSSION

   Yesterdays storm brought over a foot of low density snow to Mammoth
   Mountain. The Mammoth Lakes Basin on the south side of Mammoth Mountain
   received only 5-6 inches of new snow. The Tioga Pass region and areas
   south did not pick up measurable snow.

   Strong west and southwest winds blew most of the afternoon yesterday
   with one observer calling the spectacle a snow waterfall. These very
   strong winds loaded east and northeast facing slopes all along the
   Sierra Crest from Bridgeport to the Bishop area.

   There are several potential weak layers within the wind slab layers in
   the upper 2 to 3 feet of new snow. In some windloaded areas, snow
   depths reach 6-8 ft and deeper. The wind slab layers vary by location,
   aspect and elevation band- snowpack conditions are best described as
   variable in exposed high elevation terrain.

   Snowpack instability tests were done over the last two days. On a
   northwest facing, large open slope at treeline a layer of high density
   wind compacted snow failed in several test locations with a clean
   sliding layer of small wind hammered snow crystals. One person reported
   a rutschblock score of 4 in an open area in steep trees on the Sherwin
   Ridge with the whole block sliding off very fast. These observations
   demonstrate the variability and the continuing potential for avalanche
   release.

   Cornices are growing especially along north facing ridgetops. Many
   large cornices are overhanging north through east facing slopes. Stay
   away from these newly formed and potentially weak areas. Travel with
   reserve in steep open terrain and avoiod rollovers where slope angles
   increase and the snow is under tension.. Ride slopes one at a time and
   spot from safe zones that are well away from avalanche runouts.

   Be wary of steep open slopes at treeline and below that now have enough
   snow to ski, especially in the June Mountain area. It may be possible
   to trigger the weak snow on top of the buried rain layer from the end
   of January. Stick to small slopes and avoid convex rolls and slopes
   that funnel into a narrow gully or dense trees that would increase the
   consequences of being caught in even a small avalanche. Recent
   avalanche activity, whumpfing and cracks shooting ahead of your skis or
   sled are all signs telling you that there is a good chance of
   triggering an avalanche.

   BOTTOM LINE

   The avalanche danger is MODERATE on slopes steeper than about 35
   degrees on all mid elevation slopes at and below treeline. The
   avalanche danger rating is CONSIDERABLR on slopes steeper than 35
   degrees in wind loaded, exposed high elevation terrain. Be sure to test
   the snow as you travel by jumping on test slopes and practicing slope
   cuts. This danger rating includes the top of the Sherwin Ridge and the
   Negatives. Easy to trigger wind slabs will be found on terrain with a
   northerly, easterly and southeasterly aspects.

   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.