Avalanche Advisory for Saturday, December 29, 2007 at 6:45 am

 By Eric White 

 

 The Details:

 This Season: We had a few early season hints of snow in October, then
 a dry spell with December starting to show signs of winter. Our
 precipitation is around 87% of normal. We currently have around 3
 feet of recent snow on a thin old snow surface. We are in a "La Nina"
 climate condition which often means wetter than normal winters in our
 area and expectations are above normal precipitation into the spring
 of 2008.


 Weather Observations: We have overcast skies and air temperatures 2-6
 degrees warmer than yesterday. Mt. Shasta - We have 35 inches of
 snow on the ground near tree line with 2 inches of new snow over the
 last 24 hours. The snow settled 1 inch in the last 24 hours and
 temperatures have ranged between 14F and 25F at 7000 ft. and it is
 currently 21F. Winds this morning at tree line were estimated at
 around 30 mph from the W, and 15 mph from the SW below tree line. On
 the upper mountain winds are estimated this morning at 90 mph from the
 NW. The jet stream is overhead this morning with 146 knot winds from
 the NW. Castle/Mt. Eddy - Mt. Eddy received 1 inch of new snow in
 the last 24 hours with 1 inches of settlement. Temperatures were
 between 15F to 23F over the last 24 hours. We estimate around 2 ft.

 of snow on the ground with brush showing. Castle Lake is around 22F
 this morning.



 Weather Forecast: More unsettled weather will continue today with
 moisture coming in from the NW and W. Those directions are usually
 not favorable for precipitation on the south side of Mt. Shasta, but
 some areas in the Klamath mountains and Siskiyous will do better.

 Some lower elevation currents may drive a little more snow out of this
 system. This, along with challenges on the snow level, add some
 uncertainty to our forecast today. Warmer air is moving in, but
 trapped cold air will keep snow levels a bit lower. Today we can
 expect snow, decreasing tonight, with the snow level slowly rising
 today from 2500 ft. to 4000 ft. and dropping early tomorrow. Snow
 accumulations above 5000 ft. will vary from 1 to 5 inches with 2-3
 more likely in the Mt. Shasta back country. Temperatures at mid
 elevations will warm to the mid to upper 20's and winds below tree
 line will be 10-15 mph from the SW. Above tree line winds will be
 30-40 mph with gusts to 55 mph from the WNW. On the upper mountain
 winds will be 70-80 mph over the next 24 hours. Dry weather will
 develop Sunday through the New Year with stormy weather developing by
 the end of next week.



 Snow Pack: We have "dust on crust" again today with the best
 conditions below tree line. We have had light snow fall over the last
 few days, with accumulations of 3-4 inches and a little more expected
 today. Moderate to strong winds from the NW and W above tree line
 have created some small wind slabs on top of a crust with a weak layer
 underneath ( facets). This raises concerns for pockets of
 Considerable avalanche danger, mostly above tree line on S and E
 aspects. Below tree line, Moderate avalanche danger exists with wind
 slabs on SE, E and NE aspects.



 Some important thoughts: This advisory does not apply to Ski Areas or
 Highways and is for the Mt. Shasta, Castle Lake and Mt. Eddy back
 country. Use this information for guidance only. You may find
 different conditions in the backcountry and should travel
 accordingly. This advisory expires at midnight tonight. As always,
 use safe travel practices: travel with a partner, travel one at a
 time in suspect areas, go from one island of safety to another, choose
 safe routes, wear a transceiver, carry a shovel and probe, and know
 how to use your gear!