This is Chris Lundy of the Sawtooth National Forest Avalanche Center
 with your Backcountry Avalanche Advisory and Weather Forecast for
 Sunday, January 27, 2008 at 7:30 am.

 The Twin Falls District Bureau of Land Management & the Friends of the
 Sawtooth Avalanche Center bring you this advisory.

 Bottom Line:
 During the day today the avalanche danger is estimated to be
 CONSIDERABLE on wind loaded slopes steeper than 35 degrees and
 MODERATE on sheltered slopes. Southerly winds increased overnight
 and are expected to continue to blow during the day as a strong winter
 storm enters our area. Watch for newly forming wind slabs along upper
 elevation northerly-facing ridgelines, where they may be poorly bonded
 to the lower density or faceted snow beneath.

 A significant storm system entering our region today is expected to
 bring strong southerly winds and 12-16 inches of new snow by tomorrow
 morning. Snowfall should begin midday, and as it begins to accumulate
 this evening and overnight the avalanche danger is expected to
 increase. Avalanche danger will rise the fastest on leeward slopes
 where a combination of new and wind blown snow may overload buried
 facets layers.

 Primary Avalanche Concern:
 
 
 
 
 Southerly winds increased overnight and are expected to continue to
 blow strongly through the day. These winds will transport existing
 snow as well as the new snowfall that begins to accumulate today onto
 northerly-facing, upper elevation ridgelines and other leeward terrain
 features. Especially on steeper slopes, these wind slabs will likely
 be poorly bonded to the lighter snow beneath, or may overload buried
 facet layers. Wind transported snow may be deposited on older wind
 slabs that formed over the past several days, so the potential exists
 for these to break out fairly deep.

 Secondary Avalanche Concern:
 
 
 
 
 During our dry spell in mid-January, many snow surfaces became weak
 and faceted these were the ones that continued to provide good skiing
 and riding. Many solar aspects developed an ugly combination of sun
 crusts and facets on the surface. Other slopes, as many are painfully
 aware, got hammered by the wind into a mixture of wind crusts and hard
 slabs. These old snow surfaces were buried this past week and are now
 found about 8-12 inches deep in most locations. Matt and I taught an
 avalanche class in the Soldier Mountain area yesterday and found a
 well preserved surface hoar layer about 10 inches down. Because of the
 mixed bag of old snow surfaces, the distribution of these weak layers
 will be somewhat variable, but will be most common on wind sheltered,
 protected slopes.

 In the South and Central Valleys, and to a lesser extent further
 north, deeper facet layers close to the ground remain a concern.

 Basically, the shallower the snowpack, the more problematic these
 deeper layers will be. At low to mid elevations south of the SNRA, the
 entire snowpack has become weak and bottomless in many places.

 The storm system entering our region today will likely begin
 overloading these buried facet layers with new and wind transported
 snow. Except in wind loaded areas, I dont think enough snow will fall
 during the day today to cause a significant increase in avalanche
 danger, but as the storm intensifies overnight, you can expect an
 entirely different situation by tomorrow morning. If the weather
 forecast plays out, I would expect that overnight the avalanche danger
 will increase to High on many wind loaded slopes.

 Current Conditions:
 Our northern mountains picked up a few inches of new snow yesterday
 morning. Temperatures yesterday reached the low to mid 20s in the
 mountains and the low 30s in the valley, and currently its in the mid
 teens at most elevations. Overnight, south to southeasterly winds
 increased and are currently blowing 20-30 mph along upper elevation
 ridgelines, especially in our northern area.

 Mountain Weather Forecast:
 Low pressure systems currently off the Northwest and California coasts
 will merge today in the Great Basin, resulting in a strong
 southwesterly storm system that should bring significant snow and wind
 to our region. Snowfall is forecast to begin about midday, and by
 tomorrow morning we should pick up 12 to 16 inches of new snow.

 Ridgeline winds have already increased overnight and will continue to
 blow today at 20-30 mph with stronger gusts likely. Mountain
 temperatures should reach the low to mid 20s, and near 30 degrees in
 the valley.

 A strong cold front will pass through the area tomorrow morning,
 causing snowfall to taper off and temperatures to drop. As is
 typically the case, we can expect gusty northwesterly winds to
 accompany the frontal passage.