NW MONTANA GCAC BACKCOUNTRY AVALANCHE ADVISORY 1-23-98 This is Stan Bones with the Backcountry Avalanche Advisory for the Glacier Park and Flathead and Kootenai National Forest areas issued at 11:00 AM, Friday, January 23rd, 1998, by Northwestern Montana's Glacier Country Avalanche Center. This advisory does not apply to developed ski areas and is brought to you in part by financial grants from: --Zauner's Recreation Center on Meridian and Center in Kalispell --The Aero Inn, Highway 93 South, Kalispell --The Izaak Walton Inn located at Essex --Rocky Mtn. Outfitter, 135 Main Street, Kalispell. --The Runner-Up Sports Consignment Shop in downtown Whitefish --Ski Mountain Sports, 200 Wisconsin Avenue, Whitefish --Winter Sports, Inc. on The Big Mountain --Burlington Northern Santa Fe Railroad --The Flathead Nordic Ski Patrol --Kalispell Regional Medical Center --The Montana Department of Fish, Wildlife, and Parks --The National Forest Foundation --The Users and Supporters of the Glacier Country Avalanche Center For those of you accessing this message from within the Flathead Valley we remind you of the cheaper local access number of 257-8402. Please use only that number. We would appreciate hearing from you. After the beep please leave your suggestions for improvement of this message and your snow, avalanche, and accident observations. Names need not be given. At any time you can go directly to the beep by pressing *. If you need to talk with a real person please leave your name and phone number and we'll be in touch. In your message please include the time and date of your call. By computer we can be reached at the e-mail address of gcac@digisys.net. ******************************************************* We are currently rating the avalanche danger as generally MODERATE above 5500' in elevation and mostly LOW below that elevation. ******************************************************* WEATHER & SNOWPACK ANALYSIS Since last Monday most all mountain locations in our region have received new snowfall. New snow amounts have generally been light in the east and west portions, while the central mountain ranges of the Missions, Swans, and Whitefish have picked up much more. Electronic sensors in the Mission, Swan, and Whitefish Ranges show that these locations received between 2-3" of snow water equivalent Monday through Friday. This translates into 20+" of new snow depth. Areas in the Kootenai region and in Glacier National Park appear to have received generally only half that amount. The strongest snowfall was Monday and into Tuesday, with lighter amounts falling each day since. Sunday and Monday most all mountain locations were registering high temperatures above freezing Tuesday to Friday morning the air cooled to below freezing around the clock with daytime high temperatures being mostly from the mid to high 20's, while lows have been in the low 20's to mid teens. Winds through the period have generally been light with only the east front of the Continental Divide recording anything significant. There chinook type winds have generally been from the S-SW with gusts near 30 MPH. Backcountry tours and snowpit investigations on Thursday in the Kootenai country and east of the Divide in Glacier Park were finding that the snowpack has continued to settle and strengthen in the mid and surface layers because of the recent mild temperatures. Shallow snowpacks of 4' or less are still showing signs of weakness in the angular grains at the snow/ground interface. The other area of concern currently is the bonding between the new snows of this week and the old surface layers and within the layers of new snow themselves. Winds have generally been light except along and east of the Continental Divide. On the far east side temperatures have been warm and this has softened the new snow and old snow surfaces enough that wind transport has generally not be occurring. Along the Divide however the snowfall has been drier and lighter and wind transport has been reported. The bond strength between and within these wind deposited layers can be highly variable. ******************************************************* AVALANCHE - INSTABILITY ADVISORY Above 5500' in elevation we are currently rating the avalanche danger as generally MODERATE. Unstable slab layers are possible on slopes steeper than 35 degrees. Natural avalanches are unlikely, while human triggered avalanches are possible. Backcountry travelers should use caution in steeper terrain, especially on recently wind loaded slopes. Below approx. 5500' the avalanche danger is generally rated as LOW. Snow there is generally stable. Natural avalanches are very unlikely, while human triggered avalanches are unlikely. Backcountry travel there is generally safe. One needs to still be alert however, to large, steep, open slopes and travel on flatter slopes with steeper ones above. When traveling in the backcountry watch for signs of significant amounts of new snow loading, either from precipitation or wind deposit. Check these slopes before committing to travel or play on them. Each person in your party needs to always carry and know how to use the avalanche safety equipment of transceivers, probes, and shovels. Expose only one person at a time to a potential avalanche hazard while the remainder of the party watches from safe locations. ******************************************************* WEATHER FORECAST & AVALANCHE OUTLOOK The weather forecast is for a fast moving ridge of high pressure to pass over Northwest Montana Thursday night and Friday morning. This will be replaced by an equally fast moving disturbance Friday afternoon and night. In a tit-for-tat play, another weak high pressure ridge should rebuild Saturday morning to be replaced Saturday night by another low pressure through. This roller coaster ride of disturbance waves should give the mountains of our region several inches of new snow each day through the weekend. The snowfall amounts Friday are forecasted to be 2-3" in the mountains. This should increase Saturday to 3-5" and then slacken to 1-2" on Sunday. Temperatures during the period are expected to be slightly above normal. The freezing level will start out at 3000' Friday and is expected to rise to 5000' that day, dropping back to near 3500' Saturday, and rising slightly to 4500' Sunday. Winds this weekend may play a very significant role in snow stability and avalanche danger. Six-thousand foot winds Friday-Sunday are forecasted to be westerly between 20-40 MPH. New snowfall and wind in combination with new snowfall earlier in the week could cause the snow instability and avalanche danger to escalate this weekend. Remain alert for rapidly changing conditions. Constantly be analyzing the effects of winds upon your travel terrain. Watch also for wind loaded terrain above your travel route. ******************************************************************* This concludes the current avalanche advisory. The next regularly scheduled update will be issued at 11:00 AM, Tuesday, January 27th, 1998. For those of you with access to the World Wide Web, check out this and other avalanche advisories at www.csac.org and at www.avalanche.org. We thank all who came out Thursday night to hear and see Jack Tackle's talk and slide show of his climbing experiences over the last 30 years. It was an impressive program. The next presentation in our series on mountain adventure will be in February. Please watch for more information as the time draws near. ******************************************************************* In an effort to improve our service to the public we are attempting to define the users of this advisory message. Please stay on the line until after the beep and leave a message listing your backcountry interests. Are you a snowmobiler, snowboarder, mountaineer, snowshoer, or skier? Also let us know if you are calling from within the Flathead access area or outside and using the 1-800 number. This advisory best describes conditions at the time of its issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and a transition zone between hazards exist. Because of the general nature of the advisory, each backcountry party will always need to make their own site and time specific avalanche hazard evaluations. For current information on snow conditions stop at the Glacier Park Ranger Station at your point of entry, or call a U.S. Forest Service Office. Thank you for your support of Northwestern Montana's Glacier Country Avalanche Center. ************************************************************