Avalanche Advisory for Sunday, December 23, 2007 at 6:15am

 By Eric White

 

 The Details:

 This Season: We had a few early season hints of snow in Octobert,
 then a dry spell with December starting to show signs of winter. Our
 precipitation is around 94% 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 currently have overcast skies and warming
 temperatures. Mt. Shasta - We have 38 inches of snow on the ground
 near tree line with only a trace of new snow over the last 24 hours.

 The snow settled 2 inches in the last 24 hours and temperatures have
 ranged between 22F to 36F at 7000 ft. and it is currently 36F. Winds
 this morning at tree line were estimated at around 35 mph from the
 WNW, and up to 20 mph from the WSW below tree line. On the upper
 mountain winds are estimated this morning at 50 mph from the NW.

 Castle/Mt. Eddy - Mt. Eddy received only a trace of new snow in the
 last 24 hours with 1 inch of settlement. Temperatures warmed to 32F
 to 37F over the last 24 hours. We estimate around 2.5 ft. of snow on
 the ground with brush showing. Castle Lake is around 29F this
 morning.



 Weather Forecast: Over the next week, we will see a series of weak
 cold fronts passing through, each bringing a few inches of snow. They
 will begin warm with snow levels above town, then dropping to below
 town when the front passes. Currently, we have a system hitting most
 of the Alaskan coast, BC and Washington. It will dip through northern
 California this afternoon with snow levels starting at 6-7000 ft.,
 then dropping early tomorrow morning to town (3500 ft.). 2-3 inches
 will be possible over the next 24 hours above 7000 ft, with less
 below. Winds below tree line today will be SW at 15 mph, increasing
 late tonight to 20 mph. At tree line (8000ft.) winds will be 20-30
 mph from the W, then increase late tonight to 40 mph. On the upper
 mountain winds will be 30-40 mph from the W today and increase tonight
 and tomorrow to 60-70 mph from the W.



 Snow Pack: Temperatures began warming yesterday afternoon, but the
 powder persisted. However, with warming overnight and this morning,
 things will be heavy today with thin crusts in places. Although this
 warming isn't great for skiing and boarding, it has helped to increase
 the snow stability. Concerns remain mostly at higher elevations for
 sensitive wind slabs on E and S aspects. We had some reports of
 serious ski damage this week, so continue to watch for the barely
 covered rocks and logs.

 Photo of a Rutschblock test result on Mt. Shasta 12/21/07

 Stability tests on Friday found moderate instability near tree line in
 the top layer of new snow.

 
 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!