GNFAC Avalanche Advisory for Wed Feb 25, 2015

Not the Current Forecast

Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 25, at 7:30 a.m. Cooke City Bearclaw/Super 8 in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.

Mountain Weather

Last night 3-4 inches of snow fell in the Bridger Range, northern Gallatin Range and around Cooke City, while two inches are reported around Big Sky and a trace to an inch everywhere else.  Winds are averaging 25 mph of the N-NW with gusts of 40-50 mph. Under cloudy skies mountain temperatures are in the mid to upper teens. Today, winds will become moderate under mostly cloudy skies.  I expect another 1-2 inches falling this morning with the southern Madison Range and Lionhead area getting mostly missed.

Snowpack and Avalanche Discussion

Bridger Range   Northern Madison Range   Northern Gallatin Range   Cooke City

With the approaching storm, which I was hoping would be a little more robust, Mark and I went into the field separately to answer a simple question: Will the new snow bond to old surface? The answer we found was yes. I skied into the wind swept northern Bridger Range (Throne area) and found a highly textured snow surface and a stable snowpack. It was my first day of skiing sastrugi in years, and I really haven’t missed it. Mark found a slightly moist snow surface on a strong snowpack at the head of Little Bear in the northern Gallatin Range which mimicked what skiers found in the northern Madison Range too. Mark made a video of his findings and posted a picture of his snowpit which involved using his snowmobile to dig to the ground instead of his shovel. Further south, a report from Cooke City indicated very good stability as well.

A stable snowpack and new snow falling onto a textured or moist surface with no weak layers is good news.  Wind-loading is not. The winds have been blowing strong and loading slopes at all elevations.  Yesterday these slabs were bonding well and not easily triggered, but today’s few inches will build soft slabs that might avalanche under your skis or sled. For today, the avalanche danger is rated MODERATE on all wind-loaded terrain and LOW on all others.

Southern Madison Range   Southern Gallatin Range   Lionhead Area near West Yellowstone   

The southern Madison, Gallatin and Lionhead areas continue their drought.  A trace to one inch of new snow will hardly quench their thirst.  But the silver lining is that the snowpack continues to strengthen.  A spotty layer of buried surface hoar 1-2 feet under the surface is unreactive and will hopefully remain so throughout the season. Wind-loading is not an issue without new snow and the snowpack is only getting stronger, resting and waiting to hold the monster snowfall that’s inevitable…right? For today, the avalanche danger is rated LOW.

Mark will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.

AVALANCHE EDUCATION and EVENTS

Take a look at our Education Calendar for all classes being offered.

1-hour Avalanche Awareness, Bozeman, REI, 6:30 - 8 p.m., Wednesday, March 11.

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