Archived Advisory for Sun Feb 17 2008

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Sunday, February 17th, 2008

Good morning. This is Scott Schmidt with the Gallatin National Forest Avalanche Advisory issued on Sunday, February 17th, at 7:30 a.m. Bridger Bowl Ski Area, in cooperation with the Friends of the Avalanche Center, sponsor today’s advisory. This advisory does not apply to operating ski areas.

MOUNTAIN WEATHER

A blustery weather system moved through our area early this morning, depositing snow throughout the mountains of southwest Montana. Snowfall amounts are all over the page. The northern Bridger and Northern Gallatin Ranges received 6 – 8 inches. The mountains near Big Sky got 1 – 3 inches. Areas of the southern Madison Range, and the mountains around Cooke City got 4 – 6 inches, while the mountains near West Yellowstone only picked up an inch. Northwest winds blew 20 – 35 mph in advance of the front, with gusts up to 50 mph recorded in the Bridger Range. These winds have subsided with the frontal passage and are currently blowing 10 – 15 mph from the northwest. Mountain temperatures are in the single digits.

There will be a few lingering snow showers this morning as the system continues to push southeast. By mid-day, skies will be partly cloudy with northwest winds blowing 10 – 15 mph at the ridgetops and mountain temperatures in the mid – teens at 9000 feet.

SNOWPACK AND AVALANCHE DISCUSSION

The Bridger Range:

Two groups skiing in the northern Bridger Range yesterday reported high winds and sensitive wind slabs. One group dug a snow pit on a northeast aspect and found these wind deposits sheared clean and easy on a layer of graupel buried about a foot beneath the surface. With winds gusting up to 50 mph, and several inches of new snow to blow around, wind-loaded slopes in the Bridger Range will continue to be a concern today. A CONSIDERABLE avalanche danger exists on all wind-loaded slopes. Non-wind-loaded slopes in these mountains have a LOW avalanche danger.

The northern Gallatin and northern Madison Ranges:

Doug was in the Beaver Creek drainage near Big Sky yesterday to investigate an avalanche that caught 5 snowmobilers on Friday. The avalanche released on a layer of faceted snow approximately 3 feet from the ground, on a steep southeast facing slope that was heavily wind-loaded. The fracture broke up to 7 feet deep and propagated 250 feet across the slope. This avalanche only ran 150 vertical feet but the resulting debris was 6 – 10 feet in depth. The incident occurred when one snowmobiler got stuck on the slope. His three partners went up to help him. While they worked to free his stuck sled, a fifth ride climbed the slope about 100 feet away and triggered the slide in an area where the snowpack was thinner. All 5 riders where caught and partially buried in the resulting avalanche. Fortunately no one was injured. Images from this incident can be viewed at

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

and a video clip of Doug’s investigation can be seen at

http://www.youtube.com/watch?v=Thd5Vl7EPW4

This close call should serve as a reminded that only one person should be on a slope at any given time. If your partner gets stuck, it is up to him to free his sled. Everyone else should watch from a safe location so that they can affect a rescue if the person on the slope is caught and buried in an avalanche. Following this simple rule would cut avalanche fatalities in the U.S. by half.

A group skiing in Beehive Basin yesterday reported a layer of surface hoar is now buried beneath several inches of new snow. I was in this area on Friday. My partner and I noted this layer on the surface, mainly on slopes with a southerly aspect. I had hopes that Friday’s warm sunshine would melt this layer before it could become a problem but I guess that is not to be. This layer was also reported in the northern Gallatin Range which got substantial snow last night. Slopes that have been loaded by recent snow and strong northwest winds are likely to avalanche on this layer so dig down several feet and determine the snow stability before riding or sliding on any slopes in these areas. Today, the avalanche danger in the northern Gallatin and Madison Ranges is CONSIDERABLE on all wind-loaded slopes. A MODERATE avalanche danger exists on all non-wind-loaded slopes.

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

Doug spent two days in the mountains north of Cooke City last week. He and his partner dug snowpits on a variety of aspects and found the snowpack to be surprisingly stable given the 3 – 4 feet of snow that accumulated in these mountains during the past 10 days. Even though there are no significant weaknesses in the snowpack, slopes that have been loaded by the large amount of new snow, and the recent strong winds are still capable of producing avalanches. On Friday, a local observer reported a large human-triggered slide that released in the Sheep Creek drainage northwest of Cooke City. In addition, one of our regular observes who was skiing in these mountains yesterday reported that last nights new snow has been deposited on a sun crust that formed on slopes with a southerly aspect. Strong northwest winds have added additional load to the south-facing slopes which are likely to produce avalanche activity today. This may also be true for the mountains around West Yellowstone and the southern Madison and southern Gallatin Ranges. Today, the avalanche danger in these mountains is CONSIDERABLE on recently wind-loaded slopes steeper then 35 degree. All other slopes have a MODERATE danger.

THE 2008 KING AND QUEEN OF THE RIDGE

John Parker clinched this years King of the Ridge title with 26 hikes in the annual King and Queen of the Ridge competition held at Bridger Bowl yesterday. The Friends of the Avalanche Center’s very own Angela Patnode is this years Queen of the Ridge with 21 hikes! This year’s event drew a record crowd with 42 hikers participating to raise funds for the Friends of the Avalanche Center’s education program. Thanks to everyone who hiked and to all the folks that supported them with pledges. The money raised at this event, combined with the hard work of avalanche educators like Angela Patnode, has allowed us to extend our educations efforts throughout southwest Montana and the surrounding area. Thanks again everyone and congratulations to this years champions.

I’ll 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