15 February 2008

 Good morning. This is Ron Johnson with the Gallatin National Forest
 Avalanche Advisory issued on Friday, February 15, at 7:30 a.m.

 Moonlight Basin Ski Patrol, in cooperation with the Friends of the
 Avalanche Center, sponsor todays advisory. This advisory does not
 apply to operating ski areas.


 MOUNTAIN WEATHER

 Yesterday was the first day since February 4 that no new snow
 accumulated in the mountains of southwest Montana. Today clear skies
 will prevail and mountain temperatures will warm to the 20s F. Tonight
 a weather disturbance in northwest flow will favor the mountains
 around Bozeman with 1-3 inches of new snow by tomorrow morning. The
 rest of southwest Montana will get less than 2 inches. Ridgetop winds
 during the next 24 hours will be westerly at 15-25 mph.


 SNOWPACK AND AVALANCHE DISCUSSION

 The Bridger Range:

 Yesterday, ski patrollers at Bridger Bowl used ski cuts and explosives
 to move the few inches of snow that accumulated on Wednesday. All the
 avalanches were small and none fractured layers older than a few days.

 Strong winds early this week formed wind slabs on the lee side of
 ridges and gullies and these could avalanche. On the west side of the
 range avalanches could release on a weak layer of faceted snow
 near the ground. Today a MODERATE avalanche danger exists on
 wind-loaded slopes. Non wind-loaded slopes have a LOW danger.


 The northern Gallatin and northern Madison Ranges:

 Yesterday, ski patrollers at Big Sky saw 2 avalanches on Cedar
 Mountain that released Wednesday or early Thursday. These were on east
 facing slopes below treeline, which were recently wind-loaded. At the
 ski area, explosives triggered a few wind slabs on steep slopes.

 Otherwise, the 1-1.5 feet of snow that accumulated Wednesday behaved
 nicely and produced awesome skiing.


 I joined Karl Birkeland and a host of other snow researchers in
 Beehive Basin. I relished the opportunity to don my Sorels, grab a
 shovel and my snowpit kit and hobble a few hundred meters to a
 west-southwest facing slope, where we poke and prodded the snow in 35
 snowpits over an area of 3500 square meters. The weakest layer found
 was faceted snow near the ground. This layer didnt consistently
 fracture cleanly but remains enough of a stability problem to
 warrant caution. Today, wind-loaded slopes steeper than 35 degrees
 have a CONSIDERABLE avalanche danger. All other slopes will have a
 MODERATE danger.


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

 Yesterday, Doug Chabot and his partner were in mountains north of
 Cooke City. When their vision wasnt hampered by face shots of power
 snow, they didnt see any recent avalanches in spite of the 3-4 feet of
 snow that accumulated in this area since early February. They dug
 snowpits on northeast, southeast and north facing slopes and didnt
 find any significant weak layers.


 Yesterday, folks skiing near Bacon Rind Creek in the southern Madison
 Range found good skiing with no obvious signs of an unstable snowpack
 on east facing slopes below treeline.


 While a fairly stable snowpack seems to exist in the southern
 mountains, its worth remembering these areas have been slammed with a
 lot of new snow and wind during the past 10 days. Because of this a
 MODERATE avalanche danger exists in the mountains, which means human
 triggered avalanches are possible.