GNFAC Avalanche Advisory for Wed Feb 10, 2010

Not the Current Advisory

Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 10, at 7:30 a.m.  Jeff King at Edward Jones Investments, in cooperation with the Friends of the Avalanche Center, sponsor today's advisory.  This advisory does not apply to operating ski areas.

Mountain Weather

Under sunny skies temperatures remained cool and only rose into the teens before dropping to the single digits last night.  Yesterday, strong west to southwest winds picked up, most notably in the northern mountains.  They've been blowing 25-30 mph and will likely increase during the next 24 hours. Sunny skies will cloud up later today with temperatures reaching the low 20s.  Tonight, scattered snow showers will drop a trace to one inch of new snow with flurries continuing tomorrow.

Snowpack and Avalanche Discussion

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

Skiers found difficult travel conditions on Electric Peak in the southern Gallatin Range yesterday. Unsupportable snow, massive collapsing and shooting cracks gave them all the information they needed to turn around and head home. They also found large areas of well-developed surface hoar that looked as though someone sprinkled white corn flakes everywhere.  The southern Madison Range has similar issues.  My tour into Bacon Rind on Sunday was a carbon copy of collapsing, cracking and weak stability test scores (video).   The main layers of concern are large-grained sugary facets at the ground and a buried layer of fingernail-sized surface hoar 18 inches deep.  Clean shears, propagating fractures and low test scores all indicate you could trigger a slide, especially on a steep slope.  These mountains also have weak snow at the surface which may soon be buried by today's wind-blown snow or tonight's light snowfall.  For today, a CONSIDERABLE avalanche danger exists on any wind-loaded slope and all slopes steeper than 35 degrees.  Shallower angled slopes not affected by the wind will have a MODERATE danger.

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

In the Bridger Range yesterday, strong ridgetop and mid-mountain winds blew loose snow into drifts that were easily triggered by skiers.  Three separate folks on Saddle Peak were caught off guard as they triggered these wind slabs.  One skier was knocked off his feet, but luckily no one was caught or taken for a deadly whipper off the cliffs.  The ski patrols at Big Sky, Moonlight Basin and Bridger Bowl all noticed the formation of surface hoar and small-grained facets in the past few days which is now buried in many locations.  The Big Sky Patrol reported that higher elevation slopes may not have much loose snow to blow around, yet near treeline the Moonlight Snow Safety found crisp shears on this layer when it was capped with 2-4 inch hard slabs of wind-blown snow. On Monday skiers triggered a large avalanche on Bridger Peak (pic1, pic2) and Mark and I found recent avalanches north of Ross Peak, although these both ran on a layer of facets closer to the ground. The exact weak layer isn't important-the take home point is that it's still possible to trigger slides with wind-loaded slopes being extra hazardous to your health. Even further south in Cooke City, recent avalanche activity and reports of weak snow at the surface mirror our concerns.  For today the avalanche danger is rated CONSIDERABLE on all wind-loaded slopes and MODERATE on terrain not affected by the wind.        

Mark 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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