Thursday, February 7, 2008

 Good morning. This is Mark Staples with the Gallatin National Forest
 Avalanche Advisory issued on Thursday, February 7th, at 7:30 a.m. The
 Pinhead Classic, in cooperation with the Friends of the Avalanche
 Center, sponsor todays advisory. This advisory does not apply to
 operating ski areas.


 MOUNTAIN WEATHER

 Last night most areas only picked up a trace to 2 inches of snow;
 however, I expect that to change today. Ridgetop winds have been
 blowing 20-30 mph from west, and temperatures at 4am are in the upper
 single digits. Today, a moist west and northwest flow will bring high
 winds and snow. Temperatures will warm slightly to the teens F, and
 ridgetop winds will increase to 40 mph or more. Snowfall by tomorrow
 morning should be 4-6 inches in most areas, and the mountains near
 Cooke City could see as much as a foot of new snow.


 SNOWPACK AND AVALANCHE DISCUSSION

 The Bridger Range:

 More snow and high winds are expected to continue in the Bridger
 Range. Strong winds have created wind slabs from recent snowfall in
 unusual places, and the Bridger Ski Patrol reported they could get
 these to break. Other than the avalanche hazard of wind slabs, there
 is not much else in the snowpack of the Bridger Range that concerns
 me. Today, wind loaded slopes steeper than 35 degrees will have a
 CONSIDERABLE danger, and less steep slopes with a wind load will
 have a MODERATE danger. If you can find slopes not affected by the
 wind, they will have a LOW danger.


 The northern Gallatin and northern Madison Ranges:

 Very unstable snow can still be found in the northern Gallatin and
 Madison Ranges especially in areas with a relatively shallow snowpack.

 You can find snow depths that range from 3 - 6 feet, and stability
 that ranges from really bad to pretty good. Both Scott and Karl have
 found weak faceted snow near the ground which fractures cleanly
 and easily in stability tests. Not only will you have to look for
 these slopes with a weak shallow snowpack, you will have to watch out
 for recently wind-loaded slopes. Yesterday the Big Sky and Moonlight
 Basin Ski Patrols reported very sensitive wind slabs which should
 easily fracture under the weight of a skier or rider. Today, any
 wind-loaded slope and any slope steeper than 35 degrees will have a
 CONSIDERABLE danger. A MODERATE danger exists on less steep
 slopes without a wind load.


 The southern Madison and southern Gallatin Ranges, the Lionhead area
 near West Yellowstone, the mountains around Cooke City, and the
 Washburn Range:

 Have you started to notice a trend yet? The mountains continue to
 receive new snow which has been easily transported by the wind, and
 wind-loaded slopes present a consistent avalanche concern. Yesterday,
 Doug and his partner saw huge wind drifts in the mountains north of
 Cooke City. These drifts readily fractured under his skis but did not
 slide because he was on low angle slopes. Another group reported
 large drifts at low elevations near the Taylor Fork in the Southern
 Madison Range. Nearby, in the Bacon Rind area yesterday, my partner
 and I found good stability on non wind-loaded slopes. However, we
 saw two small, Moose-triggered avalanches on wind loaded slopes near
 the road. The two moose cows seemed unaffected by this recent
 avalanche activity as they grazed near the debris.


 In addition to reports of strong winds, weve received several reports
 of a thin layer of weak faceted snow found about 2 feet down.

 Scott found this layer in the southern Madison Range near Beaver
 Creek, I found it yesterday near Bacon Rind, and Doug found it near
 Cooke City. This layer could easily fracture and produce an
 avalanche under the combined weight of a wind slab and a skier or
 rider. For today, all wind loaded slopes have a CONSIDERABLE
 danger and slopes with out a wind load have a MODERATE danger.