GALLATIN NATIONAL FOREST AVALANCHE ADVISORY FRIDAY, FEBRUARY 21ST, 1997 Good morning, this is Karl Birkeland with your Gallatin National Forest Avalanche Advisory issued on Friday, February 21st, at 7:30 AM. The next advisory will be issued tomorrow morning. Today's advisory is sponsored by Montana Fish, Wildlife and Parks Snowmobile Safety Program. These advisories do not apply to the operating ski areas. Yesterday was a mixed bag of moderate weather, with some sun, some clouds, some wind, and a few snow showers dropping an inch of snow in a couple places. There are a couple weather systems around today, but I think we will be mostly out of the action and we should have mostly sunny to partly cloudy skies, mountain temperatures into the mid- to upper-20's, and ridgetop winds out of the northwest and west at 10 to 20 mph. A small disturbance will pass by tonight and give us some clouds and maybe a couple snowflakes, but I wouldn't think we would get more than an inch or possibly two. Yesterday Ron and I headed down to Lionhead. We saw a large natural avalanche on an east to northeast facing slope at 9000 feet that probably released Wednesday night. The slide looked like it was triggered by a cornice fall, and it released on a slope that was steep - between 35 and 40 degrees. We dug several snowpits and concluded that, despite this avalanche, the snowpack was strengthening. It seems like some of the areas that are below treeline and protected from the wind have the weakest weak layers, while some of the areas above treeline have stronger weak layers, but larger deposits of windblown snow. This is making for a bit of a tricky situation in terms of evaluating the avalanche danger on a particular slope. All in all, there is no clear cut pattern to our current avalanche danger. I believe that many slopes out there are becoming quite a bit more stable and will support the weight of a skier or snowmobiler. We saw this in action yesterday as several people highmarked a number of slopes at Lionhead that did not slide. Still, I believe that there will be a number of slopes out there where you could trigger an avalanche. This scattered pattern of instability makes me nervous. FOR TODAY I WOULD CALL THE SNOWPACK INSTABILITY MOSTLY MODERATE-TO-HIGH ON ALL SLOPES STEEPER THAN 40 DEGREES, AND MOSTLY MODERATE ON GENTLER SLOPES IN THE BRIDGER, GALLATIN, MADISON, AND WASHBURN RANGES, THE LIONHEAD AREA, AND THE MOUNTAINS AROUND COOKE CITY. Today would be a good day to use caution on all steep slopes...make sure you only expose one person to the avalanche danger at a time, and be sure to carry avalanche rescue gear and know how to use it...because even during periods of low or moderate avalanche danger, avalanches are still possible and you have to use caution. Wednesday night. With the new snow we've had over the past week, the skiing and snowmobiling conditions are great. I had a great report from Cooke City yesterday of good skiing conditions and a slowly stabilizing snowpack - and the skiing and riding conditions on Lionhead were also excellent. Ron will issue the next advisory tomorrow morning. If you have any recent snowpack or avalanche information to pass on, please give us a call at 587-6984, or log on to the internet and e-mail us from our home page. This advisory is also available on a recorded message at 587-6981 in Bozeman, 838-2341 in Cooke City, and 646-7912 in West Yellowstone. Advisories are available on the Internet at http://www.csac.org (where you can also subscribe the advisories by e-mail). You can also find our advisories and other useful information at our web page at http://www.avalanche.org/~gnfac.