This is Matt Lutz of the Sawtooth National Forest Avalanche Center with
 your Backcountry Avalanche Advisory and Weather Forecast for Thursday,
 February 21, 2008 at 7:30 am.

 The Sun Valley Telemark Series & Smiley Creek Lodge & the Friends of
 the Sawtooth Avalanche Center bring you this advisory.

 Bottom Line:
 Today in the South Valley, Central Valley and Soldier Mountain area the
 avalanche danger is estimated to be LOW. The avalanche danger on
 solar aspects and slopes that have obvious large wind pillows will move
 to MODERATE with daytime heating.

 The avalanche danger in the North Valley and Sawtooth Mountains is
 estimated to be LOW. The avalanche danger on solar aspects in these
 areas will move to MODERATE with daytime heating.

 Primary Avalanche Concern:

 
 

 

 

 Overnight our forecast area had a good freeze and today the
 temperatures are only expected to reach the high 20s to low 30s at
 higher elevations. Overall as long as temperatures stay relatively cool
 I do not expect to see much avalanche activity. Solar aspects will have
 an increasing danger trend as they pick up heat through the day.

 Folks on skis and sleds have been going into some big and steep terrain
 lately and we have not had any recent reports of human triggered slides
 as a result. This is strong evidence that the snowpack is in a state of
 balance. As you go into bigger, steeper and more committing terrain be
 sure to use good mountain travel techniques. These techniques include
 only exposing one person at a time, using good communication within
 your group, having the appropriate safety gear, and avoiding terrain
 traps.

 Secondary Avalanche Concern:

 
 

 

 
 In the South Valley, Central Valley and Solider Mountain area the
 snowpack is thin, variable and weak. Most slopes in these areas have a
 generally poor structure with a slab sitting on a weaker layer of snow
 near the ground. Areas of particular concern are steep slopes that have
 obvious large wind pillows.

 In the North Valley and Sawtooth Mountains most southern aspects still
 have a crust facet interface approximately 2 feet deep. This interface
 is still producing easy to moderate clean shears with stability tests.

 Southern slopes should be approached with caution especially through
 the warmer hours of the day.

 Additional Discussion
 Working and recreating in the realm of snow is so interesting and I
 learn something new each season. The current situation especially in
 the southern terrain is particularly interesting. In these areas there
 is currently a widespread weak layer of facets on the ground, a slab of
 snow above it, large wind pillows; there has been recent heating and
 many triggers, but no recent avalanching? It leaves me scratching my
 head as to why? Frankly I do not know the answer. We do our best to
 call the kettle black when it is and that is why today I estimate the
 danger to be LOW.

 The one thing I do know is that you just cannot trust persistent weak
 layers and these layers are still within the snowpack in many places
 throughout our forecast area. When winter kicks in again and we get
 more precipitation I suspect that we could see these persistent weak
 layers come back to life. Time will tell.

 Current Conditions:
 Low to mid elevations and solar aspects have a wide spread crust on the
 surface. Some immature corn snow is out there especially on steep due
 south aspects. If you can hit these slopes within the right morning to
 midday window you will have some fun. For folks who see their glass as
 half full, sheltered shady slopes will provide some reasonable riding
 conditions.

 Ketchum is under blue skies this morning with a 6 am temperature of 7
 degrees. Upper elevation ridgeline temperatures are in the low to mid
 20s. Winds are calm to very light out of the southeast.

 Mountain Weather Forecast:
 Today expect mostly clear skies as the high pressure will continue
 through the day. Ridge top high temperatures will be in the high 20s to
 low 30s. Winds are expected to be calm to light out of the southeast
 through today. Late tonight a low pressure trough will push into our
 forecast area. Light snow is expected to begin by early tomorrow
 morning. The Sawtooth Mountains may see up to 3 to 5 inches by Friday
 night. Another weak system is expected to roll in by Saturday night.