GALLATIN NATIONAL FOREST AVALANCHE ADVISORY WEDNESDAY, MARCH 25th, 1998 Good morning, this is Doug Chabot with your Gallatin National Forest Avalanche Advisory issued on Wednesday, March 25th at 7:30 am. The next advisory will be issued tomorrow morning. Today's advisory is sponsored by the Friends of the Avalanche Center with a matching funds grant from the National Forest Foundation. These advisories do not apply to operating ski areas. First off we'd like to thank Gordon Wiltsie and Alex Lowe who, through the Friends, put on an exceptional slideshow last night at the Emerson Cultural Center. The stories and photos were outstanding. If you were one of the 5- 600 people that showed up, thanks for your support. Given the wet weather we've been having umbrellas, rain slickers and galoshes are becoming required outdoor gear. In the last 24 hours the northern mountains got anywhere from .2-.8 inches of rain. In the extreme southern areas this moisture fell in the form of snow in the higher elevations. The mountains around Cooke City and West Yellowstone got about 4-6 inches above 8000 feet. This gives them a new snow total since Monday of 6-12 inches. At least snow has been falling somewhere in our region! Last night was the first evening in 4 nights where the temperatures dipped to below freezing. Most areas had about 6-10 hours of temperatures of 32 or below. The daytime highs should be similar to yesterday with mountain temperatures in the low 40's. Skies should stay mostly cloudy today with decreasing clouds tonight and freezing temperatures again. The northern mountains can expect another .1-.2 inches of water, most likely in the form of rain below 8000 feet. In the south they could see 2-4 more inches of snow by morning. Winds will be out of the southwest at 10-20 mph, changing to more westerly by tonight. Looking out a few days, the models are showing us setting up in a northwest flow by Friday morning which should bring cooler temperatures back to our area. With the warm weather and above freezing temperatures at night the snowpack has been ripe for some rather large wet avalanches. We received a report of some sizable slides off of highway 191 near Greek Creek. The ski areas have miraculously been holding their own with few wet slides. But the snowpack has gone isothermal in many areas. This means that a temperature profile shows 0 degrees Celsius throughout the entire snow column which significantly decreases the strength of the snowpack. You can tell that this is happening when you're skis start to punch through and sink to the bottom. Isothermal snow can't support skiers or snow machines too well. And this means that if the slope is steep enough it would be dangerously close to sliding. The strength that the freezing temperatures provided will disappear as the temperatures warm up. If you're in the backcountry and your skis start to sink signifying the melting of the upper crust, be aware that the avalanche danger is rising rapidly. FOR TODAY, FOR THE BRIDGERS, MADISON AND GALLATIN RANGES THE WET SNOW AVALANCHE DANGER IS LOW FOR THIS MORNING BUT INCREASING TO CONSIDERABLE AS THE SURFACE CRUST MELTS. With the new snow that's fallen down south the instability to watch out for is the bonding that's taking place with the new snow to the ice crust as well as the density changes within the fresh snow. People had great skiing conditions yesterday out of Cooke City at the higher elevations. They did feel some isolated collapsing of the snowpack, but saw no avalanche activity. Given that its snowed upwards of 12 inches, FOR TODAY, FOR THE MOUNTAINS AROUND COOKE CITY, THE LIONHEAD AREA NEAR WEST YELLOWSTONE AND THE WASHBURN RANGE, THE DRY SNOW AVALANCHE DANGER WOULD BE MOSTLY MODERATE. I will issue the next advisory tomorrow morning. If you have any snowpack or avalanche information to pass on, please give us a call at 587-6984 or send us e-mail. This advisory is also available on a recorded message at 587-6981 in Bozeman, 646-7912 in West Yellowstone, and 838-2341 in Cooke City. You can also reach us from our home page at http://www.gomontana.com/avalanche. You can also find a bunch of great avalanche information at http://www.avalanche.org and http://www.csac.org. END