GNFAC Avalanche Advisory for Tue Feb 9, 2010

Not the Current Advisory

Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, February 9, at 7:30 a.m.  Montana Ale Works in cooperation with the Friends of the Avalanche Center, sponsor today's advisory.  Special thanks go to Albert and Chef Roth of Ale Works for organizing a successful five-course dinner fund raiser last night.  This advisory does not apply to operating ski areas.

Mountain Weather

Although it was sunny in the mountains, the Gallatin Valley was under a low ceiling of clouds yesterday.  These clouds and fog will persist until this afternoon when sunny skies will prevail. Mountain temperatures are in the single digits this morning but will warm into the low twenties.  Ridgetop winds have picked up slightly and are blowing west to southwest at 15-20 mph.  Under clearing skies there's no snowfall in the forecast until Thursday.

Snowpack and Avalanche Discussion

The southern Madison Range, southern Gallatin Range and the Lionhead area near West Yellowstone:

The southern mountains continue to keep me on my toes.  A group of us toured into Bacon Rind in the southern Madison Range on Sunday.  We had acres rumble and collapse under our feet as we skinned uphill. In the first snowpit our stability test had no clean fractures-it was showing stability. We all laughed at the ridiculously strong test score; surely it was wrong.  Not to be fooled we dug another and got a very clean shear indicating the poor stability we expected.  The first test is a "False-Stable" (article) and is a perilous finding since it can lure us into thinking a slope is stable when it's not.  All the collapsing and cracking indicated bad, unstable, potentially dangerous conditions.  We found fingernail sized surface hoar buried 18 inches down that scared us into skiing a shallow angled line (video and picture of our tests and snowpit).

Further south near Hebgen Lake a group of skiers found the surface hoar too.  They got these feathery crystals to propagate a fracture in all eight of their stability tests.  The snow is not just weak; it's unstable and could avalanche.  I have yet to ski or ride a steep slope in the southern mountains this winter.  Patience is the companion of wisdom, so I'm waiting for better times.

Today, the avalanche danger is rated CONSIDERABLE on all slopes steeper than 35 degrees. All other slopes are rated MODERATE.                      

Bridger, northern Madison, and northern Gallatin Ranges, mountains around Cooke City and the Washburn Range:

A group touring south along the Bridger ridge crest triggered a large slide yesterday on Bridger Peak.  They've been in this area many times and were not planning on skiing anything too gung-ho. Although they typically stick to a conservative line, they nibbled around the edges of the steeper slope yesterday and got it to avalanche during a strong ski cut. Check out the photo of the boarder releasing the slab and a picture of the crown.  It broke over two feet deep, pulled out 200 feet wide and ran about 1,800 feet--almost full track.  It broke on facets near the ground and they were able to trigger it on a thinner part of the slope.  Yesterday, Mark and I found a similar snowpack in the northern Bridger Range where in the last few days snowmobilers triggered avalanches that propagated 400 feet wide on this faceted layer.  As the days pass without snow, folks are venturing further afield in search of untracked powder.  The ski and riding conditions are great and most slopes are getting safe tracks.  But as these avalanches forcefully show, there are still slopes that are ripe to slide if you hit them in just the right spot. And these aren't small pockets; they're full track slides.  Even outside Cooke City where the snowpack is 4-5 feet deep, riders are still triggering avalanches on some slopes (picture).  Although small, they warn us of the possibility of something bigger releasing too. Climbers in Hyalite had a scare on Sunday when a slope above them avalanched seconds after the last person reached safe ground.  

Today the avalanche danger remains an honest-to-God MODERATE on all slopes.  A Moderate danger means human triggered avalanches are still possible, which, given our recent activity, seems to be spot on.    

I will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry let us know what you find.  You can reach us at 587-6984 or email us at mtavalanche@gmail.com.

8th ANNUAL KING AND QUEEN OF THE RIDGE

We need pledges.  All three of us will be hiking the ridge for dollars this Saturday.  You can sponsor all three of us, just one or donate a flat fee.  It's easy; just drop us a note with your wishes and we'll let you know how it goes.  Mail us at mtavalanche@gmail.com.  The K&Q of the Ridge raises money that's used exclusively for avalanche education. 

You can also make a donation to Team Tyler in memory of Tyler Stetson. Tyler was killed in an avalanche in Beehive Basin in January 2008. Team Tyler is comprised of family and friends who are traveling to Bridger Bowl from all over the country to compete and honor Tyler's life.

Avalanche Education

1. Cooke City Fire Hall

One Hour Avalanche Awareness Class - Saturday, February 13th 6:30 pm to 7:30 pm

2. Bridger Bowl

AAI Level 1 Avalanche Course - Friday, February 19th to Sunday, February 21st  

www.americanavalancheinstitute.com

3. Bridger Bowl

AAI Level 2 Avalanche Course - Monday, February 22nd to Thursday, February 25th

www.americanavalancheinstitute.com

4. Moonlight Basin

Comprehensive avalanche awareness class - Thursday, March 4th to Saturday, March 6th

events@moonlight.com or 406-993-6026


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