GNFAC Avalanche Advisory for Fri Jan 13, 2017

Not the Current Forecast

Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Friday, January 13th at 7:00 a.m. Today’s advisory is sponsored by Grizzly Outfitters in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.

Mountain Weather

High pressure will be the dominant weather pattern over the next few days. This will result in clear skies, calm winds and strong temperature inversions. At 5 a.m. temps are in the single digits above zero and winds are blowing 5-20 mph out of the W-SW. Today, there will be plenty of sunshine and temps will warm into upper teens to mid-20s F. Winds will remain light to moderate out of the W-SW.

Snowpack and Avalanche Discussion

Cooke City

After the biggest storm of the year, the snowpack is getting a break. It has been over 24 hours since the snow stopped and winds have diminished significantly. Without active loading, natural avalanches are less of a concern, but human triggered avalanches remain likely. A large natural avalanche on the SE face of Scotch Bonnet two days ago is a good reminder of what’s still possible (photo, video).

Slides failing of a layer of facets buried 2-3 feet deep is the main problem (photo, video). This layer exists on all aspects and elevations and should be thoroughly evaluated before committing to steeper slopes. Given the sheer volume of snow that fell earlier in the week (over 3 feet), slopes do not need to be wind loaded to be unstable.

Slides failing on weak snow near the ground also remain a possibility. If a slide fails on this layer it will be large and destructive. I recommend avoiding steep, rocky terrain where it will be easier to impact this weak layer.

Today, cautious route finding and conservative decision making are essential. Natural avalanches are possible and human triggered avalanches remain likely. For this reason the avalanche danger is rated CONSIDERABLE on all slopes.

Bridger Range   Madison Range   Gallatin Range  

Lionhead area near West Yellowstone

The snowpack structure is not great (video), but weak layers buried mid-pack and near the ground held up surprisingly well to the recent storm. Over the past few days I’ve skied near Hebgen Lake and Bacon Rind and observed no natural avalanches or obvious signs of instability. I did get unstable results in a stability test yesterday at Bacon Rind on a layer of facets buried about a foot deep. Alex got similar results yesterday in Beehive Basin (video).

Fractures are propagating on the new snow/old snow interface which is now buried 12-18” deep. Although we’re getting unstable results in stability tests, the lack of avalanche activity and signs of instability such as cracking and collapsing are good indicators this layer is not highly unstable. With that said, I would still do your homework and assess each slope carefully before jumping into steeper terrain. Weak facets near the ground still exist and slides failing on this layer can’t be ruled out.

Today, facets buried mid-pack and near the ground continue to make human triggered avalanches possible and the avalanche danger is rated MODERATE.

I will issue the next advisory tomorrow morning by 7:30 a.m.

We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.

Upcoming Events and Education

Month of January: Montana Ale Works has chosen the Friends of the Avalanche Center as January's "Round It Up America" recipient. Every time you round-up your bill the change gets donated to the Friends. Pennies equal dollars!

King and Queen of the Ridge, Saturday, February 4th. A Hike and Ski/Ride-a-Thon fundraising event to support the Friends of the Gallatin National Forest Avalanche Center. Register with Bridger Bowl HERE, make pledges HERE.

BOZEMAN

Today and Saturday, January 13 and 14, Companion Rescue Clinic, REI Friday 6 p.m., field Saturday TBA. Register here: https://events.ticketprinting.com/event/21313.

Tuesday, January 17, Avalanche Center Forecaster’s Social at Montana Ale Works. A small-plate fare and beer tasting fundraiser for the Friends: $40.00/person; 2 seatings (5:30 p.m. and 7:00 p.m). Get your tickets HERE.

Evenings 18-19 January, field 21 or 22 January. Introduction to Avalanches with Field Course, 7-9:30 p.m. at MSU Sub Ballroom B. Sign up HERE.

COOKE CITY

Weekly rescue training and snowpack update, 6-7:30 p.m., The Antlers Lodge on Friday, field location Saturday TBA.

BIG TIMBER

Tuesday, January 17, Avalanche Awareness, 6-7:30 p.m., Sweet Grass County High School.

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