Archived Advisory for Thu Jan 1 2009

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1 January 2009

Happy New Year. This is Ron Johnson with the Gallatin National Forest Avalanche Advisory issued on Thursday, January 1 at 7:30 a.m. Northern Lights Trading Company, in cooperation with the Friends of the Avalanche Center, sponsor today’s advisory. This advisory does not apply to operating ski areas.

AVALANCHE WARNING

A Backcountry Avalanche Warning continues for the southern Gallatin and southern Madison Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range in northern Yellowstone National Park. New snow and strong winds continue to load a snowpack that has produced numerous avalanches during the past week. Today more snow and wind is forecast and the avalanche danger remains HIGH on all slopes. Areas of unstable snow are common. Natural and human triggered avalanches are likely. Avalanche terrain including avalanche runout zones should be avoided.

MOUNTAIN WEATHER

During the past 24 hours, 8-10 inches of snow accumulated in the mountains around Cooke City, and 2-3 inches fell in the mountains around Big Sky. Less than an inch of new snow fell in the mountains around Bozeman and West Yellowstone. While new snow amounts varied in the mountains of southwest Montana, west to southwesterly ridgetop winds speeds were consistently blowing 30-50 mph. Today a strong westerly flow will bring Pacific moisture into southwest Montana. By tomorrow morning, the mountains around Cooke City will get 8-12 inches of new snow, 6-8 inches will cover the mountains around West Yellowstone, and 3-6 inches will accumulate in the mountains around Big Sky and Bozeman. Westerly ridgetop winds will howl at 30-50 mph and mountain temperatures will warm to the 20’s F.

SNOWPACK AND AVALANCHE DISCUSSION

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

Today begins a new year but unfortunately the snowpack in the mountains around Cooke City and West Yellowstone retains last year’s instabilities. Reminders of these instabilities include a human triggered avalanche near Cooke City on Tuesday as well as several naturally released avalanches earlier this week; including ones on Fisher Peak and Sheep Mountain which can be viewed at:

http://www.mtavalanche.com/photos/photos.php

Yesterday snowshoers in the mountains north of West Yellowstone notice a small avalanche released during the past few days on a low elevation, recently wind-loaded slope. Faceted snow surrounding an ice layer buried 2-4 deep remains the weakest layer in the snowpack and with today’s forecast of new snow and strong winds the avalanche danger will remain HIGH on all slopes.

The Bridger, northern Madison and northern Gallatin Ranges:

Yesterday Doug and I teamed up with the assistant snow safety director at Bridger Bowl and we ventured onto the west side of the Bridger Range. We encountered wind raked snow with numerous wind slabs and wind crusts. We didn’t notice any recent avalanches or cracking or collapsing of the snowpack but stability tests indicate the less dense snow under the wind slabs is a weak layer worthy of concern. A similar weak layer was observed by skiers north of Bridger Bowl.

Ski patrollers at Big Sky and Moonlight Basin continue to express concern about weak snow surrounding ice crusts located 1-2 feet above the ground; though, most recent avalanches, including several yesterday, have occurred on steep wind-loaded slopes. These fractured on less dense snow underlying wind slabs. A snowmobiler on Buck Creek Ridge saw an avalanche that recently released on wind-loaded slope. He sent us a photo that can be viewed at:

http://www.mtavalanche.com/photos/photos.php

Today, a CONSIDERABLE avalanche danger exists on all wind-loaded slopes. Non wind-loaded slopes have a MODERATE danger.

PLEASE NOTE

Today is the forth day in a row an avalanche warning has been issued. Please don’t be like the dog that after a while only hears his master say Blah, Blah, Blah, Blah, Blah. Please heed the warning and temper your New Year’s Day desire to play on steep slopes. Cheers to a safe and healthy 2009!

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