Archived Advisory for Wed Jan 30 2008

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WEDNESDAY, JANUARY 30

Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, January 30th, at 7:30 a.m. Bridger Bowl, in cooperation with the Friends of the Avalanche Center, sponsor today’s advisory. This advisory does not apply to operating ski areas.

MOUNTAIN WEATHER

In the last 24 hours, 4 inches of 7% density snow fell in the mountains around Big Sky and the southern Madisons while 6-8 inches accumulated near Lionhead and Cooke City. Mountain temperatures rose into the double digits yesterday with strong westerly winds. Last night these subsided to 15-20 mph, but will increase out of the southwest later today under mostly cloudy skies as mountain temperatures warm into the teens. By tomorrow morning I’m expecting another 1-3 inches of new snow around Big Sky and further south.

SNOWPACK AND AVALANCHE DISCUSSION

The Bridger Range:

There was no new snow in the Bridger Range last night, but the 5 inches of powder from the day before got blown around from the strong westerly winds. Cornices grew and wind pillows thickened, but the Bridger Ski Patrol found these to be relatively stable. Other than a few isolated pockets of surface hoar buried 8-12 inches deep, there aren’t any layers we’re overly concerned with. Just be careful on steep wind-loaded slopes and poke your hand or pole into the snow to avoid the buried surface hoar. For today the avalanche danger is rated MODERATE on wind-loaded terrain steeper than 35 degrees. All other slopes will have a LOW avalanche danger.

The northern Gallatin and northern Madison Ranges:

The mountains around Big Sky picked up 4 inches of snow last night while the northern Gallatin Range got a trace. The slopes in these northern mountains have weak, unstable snow buried 1-2 feet off the ground. This layer of faceted snow is still fracturing clean in our stability tests, and even more importantly, are still avalanching from human triggers. The snowpack is more variable than normal and I don’t trust it. Do not rely on a single stability test as a “green light” to hit a slope. On Monday, I dug a snowpit on Mt Blackmore which showed relatively stable conditions, yet not far away a cornice drop triggered a slope which killed a dog. Ten days ago in Beehive Basin, where a skier was killed in a slide, Scott found areas of the slope which were quite weak, yet only a hundred feet away he tested snow that was relatively strong. Subtle differences in terrain affect the snowpack. For today, because human triggered slides are still probable, the avalanche danger is CONSIDERABLE on anything wind-loaded as well as any slope steeper than 35 degrees. All other slopes will have a MODERATE avalanche danger.

The southern Madison and southern Gallatin Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City, and the Washburn Range:

The southern mountains continue to get snow. Carrot Basin in the southern Madison Range got another 4 inches, while the mountains around West Yellowstone and Cooke City got 6-8 inches. A lot of weight has been added to the snowpack in the last 3 days with storm totals in the 2-3 foot range. Strong westerly winds are only making matters worse. A thin layer of faceted snow 2-3 feet from the surface will be fracturing with this new load, especially on slopes with wind drifts. If the visibility gets good, I expect you’ll see natural avalanche activity on steep slopes. Given the new snow, wind and buried weak layer, I recommend staying out of avalanche terrain today including being extra cautious near runout zones. For today, the avalanche danger is rated HIGH on all slopes steeper than 35 degrees. Less steep slopes will have a CONSIDERABLE danger.

Ron Johnson will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry give us a call or email with your observations. You can reach us at 587-6984 or email us at mtavalanche@gmail.com

AVALANCHE EDUCATION

The ASMSU Outdoor Recreation Program sponsors an Advanced Avalanche Awareness Seminar tonight and Thursday in the SUB at MSU from 7:00 p.m. to 9:30 p.m. An all day field session will be held at Bridger Bowl this Saturday, February 2. This course is open to the public; however, enrollment is limited and pre-registration is required. Call 994-3621 for more information.

KING AND QUEEN OF THE RIDGE

The 5th Annual King and Queen of the Ridge, held at Bridger Bowl on Saturday, February 16th, is a huge fundraiser for the Friends of the Avalanche Center. ALL proceeds promote avalanche education in southwest Montana. To date they have raised over $46,000 with this event. This winter the Friends have directly sponsored over 28 lectures reaching 1000+ people—and the season is far from over!

You can help in 2 ways:

1. Get pledges and hike the ridge. You don’t have to do 20 laps—you can get flat pledges and hike just once! Or you can test your mettle and try and break John Yarington’s record of 27 laps in 5 hours.

2. Sponsor someone. If you don’t have someone to sponsor, consider sponsoring either Scott or Doug.

Go to http://www.bridgerbowl.com/events/view_event/15/ for more information and registration forms. Poster: http://mtavalanche.com/data/images/1201700072.jpg