GNFAC Avalanche Advisory for Sat Feb 4, 2012
US Avalanche Danger Scale
GNFAC Web Site

Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Saturday, February 4 at 7:30 a.m.  Gallatin County Search and Rescue in partnership with the Friends of the Avalanche Center sponsors today’s advisory.  This advisory does not apply to operating ski areas. 

Mountain Weather:
A ridge if high pressure is dominating the weather pattern.  Currently, skies are clear, temperatures are in the mid teens F and winds are blowing out of the WNW at 5-15 mph.   Today will provide plenty of sunshine allowing temperatures to climb into the mid 30s F.  Winds will stay light out of WSW.  Clear and calm weather will continue through the weekend.

Snowpack and Avalanche Discussion:
The southern Madison and southern Gallatin Ranges, the Lionhead area near West Yellowstone and the mountains around Cooke City:

The avalanche danger around Cooke City is deceiving.  Fresh snow on top of a supportable slab is making travel easy, allowing skiers and riders to venture further into avalanche terrain.  While conditions look and feel great – there is a significant problem lurking deep within the snowpack. 

A layer of weak facets buried beneath a 3-4 foot slab is producing dangerous avalanche conditions (video).  On Friday, I triggered a large slide on the south face of Mt Abundance from low on the slope.  This slide was triggered in an area where the snowpack was only ankle to knee deep (photo, photo). 

Deep slab instabilities are tricky and very dangerous.  It often takes finding the “sweet spot” to trigger a slide.  Areas where the snowpack is thinner, specifically around rock bands and tree outcroppings will be likely trigger points.  While conditions may feel stable they are not. This avalanche is a major warning sign and evidence of what’s possible on other slopes. 

The snowpack near the Taylor Fork and West Yellowstone is just as weak and unstable.  Over the past few days multiple natural and human triggered avalanches have been observed in the area.  A cohesive slab 1-3 feet thick is resting over weak snow near the ground making the snowpack sensitive to the weight of a skier or rider.  Slopes steeper than 35 degrees and all wind loaded slopes will be especially avalanche prone.

Today, dangerous avalanche conditions exist and the avalanche danger is CONSIDERABLE.

The Bridger Range and northern Madison Range:

Today’s primary avalanche concern in the northern Madison Range will be wind loaded slopes.  South winds over the past few days transported snow from Thursday onto north facing slopes, producing sensitive soft slabs.  Yesterday, the Moonlight Basin Ski Patrol triggered multiple small to medium sized avalanches in upper elevation, north facing terrain.  These slides were confined to the new snow and nothing stepped down to deeper layers. 

In the Bridger Range, slopes directly below the ridgeline, specifically in steep-rocky terrain will be the most likely to produce an avalanche (video).

All the ingredients for avalanches are present making human triggered avalanches possible and the avalanche danger is rated MODERATE.

The northern Gallatin Range:

The northern Gallatin Range especially the Hyalite Canyon area has received more consistent snowfall throughout this season.  This snowfall has been just enough to build a snowpack lacking widespread weak layers.  Today, slopes steeper than 35 degrees have a MODERATE avalanche danger.  Slopes less than 35 degrees have a LOW avalanche danger.

I 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.

FUNDRAISING

Today: Poker Run

The Gallatin Valley Snowmobile Association is sponsoring their annual Buck Ridge Poker Ride this Saturday. All proceeds benefit the Friends of the GNFAC. Registration is at 9 a.m. in the Buck Ridge parking lot.  More info at www.gvsa.net

February 8: 4th Annual Montana Ale Works Wine Dinner

Join us for a wonderful evening with a multi course dinner and wine parings created just for this event at Montana Ale Works.  Menu and ticket information is here:  http://bit.ly/wEg01j

February 11: 10th Annual King and Queen of the Ridge

The 10th Annual King and Queen of the Ridge Hike/Ski-a-thon fundraiser is Saturday, Feb 11th.  The event supports avalanche education in southwest Montana. Collect pledges for one, two or the most Ridge hikes you can do in the five hours of competition. 100% of the proceeds go to the Friends of Gallatin National Forest Avalanche Center. Kids and families are encouraged to hike too!  More Information / Registration Form

EDUCATION

Bozeman

FREE 1-hour Avalanche Awareness at REI on Thursday, February 16 at 6:30 p.m.  For more information call REI at 406-587-1938

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