Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Forecast on Wednesday, November 30th at 7:00 a.m. This information is sponsored by Yellowstone Club Community Foundation and Grizzly Outfitters. This forecast does not apply to operating ski areas.
*Note: Bridger Bowl Ski Area is closed and there are no avalanche control or ski patrol services. Backcountry conditions exist. Please don’t ski over hoses and power cords, stay off chairlifts, and give snowcats and snowmobiles plenty of room.
At 5 a.m. the mountains around Bozeman and Big Sky received 1” of new snow while West Yellowstone and Cooke City picked up 2”. Temperatures are in the low single digits F and wind is averaging 15-30 mph with gusts of 50 mph out of the W-SW. A strong, moist, southwest flow will bring snowy weather through Friday. By morning I expect 1-2” around Bozeman and Big Sky and 6” in the southern mountains including Cooke City.
There is 1-2” of new snow and more is on the way. Wind is strong with gusts of 40-50 mph at ridgetops, mostly from the southwest. Today, new snow and strong wind will create drifting at all elevations. These thicker slabs of snow could be triggered. Over the weekend skiers released avalanches on wind-loaded slopes in the Bridger Range and in Hyalite (avalanche activity log). At Lionhead on Monday, Dave and his partner triggered 5 loud “whumpfs” which is when a weak layer collapses and propagates (video and observation). Think of a whumpf as an avalanche on the flats. This is a red flag warning to avoid avalanche terrain. The collapsing weak layer is feathery crystals of surface hoar buried 1-foot deep and we assume it can be found in nearby ranges.
Yesterday, Dave and I went into Beehive Basin and found relatively stable conditions (video). Soft snow on the surface will continue to get blown into thicker drifts that could be triggered. Shooting cracks or collapses (whumpfs) in these drifts are signs of instability. I recommend digging down to see what is under your feet or sled. A weak layer of surface hoar or a propagating extended column test should turn you around.
For today, the avalanche danger is rated MODERATE since human triggered avalanches are possible. If it snows more than expected in the Lionhead area the avalanche danger will rise to Considerable.
If you get out, please share avalanche, snowpack or weather observations via our website, email (firstname.lastname@example.org), phone (406-587-6984), or Instagram (#gnfacobs).
Today will be snowy in Island Park. Winds are strong and gusting to 50 mph at the ridgetops, mostly from the W-SW, building drifts at all elevations. These thicker slabs of snow could be triggered. Shooting cracks or collapses (whumpfs) in these drifts are signs of instability (video). I recommend digging down to see what is under your feet or sled. A weak layer of surface hoar or a propagating extended column test should turn you around.
Request: If you get out riding, let us know if you find a layer of buried surface hoar (feathery crystals) about 1-foot under the surface. If so, beware of steep slopes and runout zones as they could avalanche with more snow or wind-loading. Submit your observations here.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Monday, December 5, 6:30-7:30 p.m. @MAP Brewing in Bozeman, Know Before You Go avalanche awareness presentation.
Tuesday, December 6, 9 a.m. - 3:00 p.m. West Yellowstone Avalanche Fundamentals w/ Snowmobile Field Session. Pre-register HERE.
Thursday, December 8, 6 - 7:30 p.m., Free Snow & Avalanche Safety Workshop: Belgrade Community. This workshop will cover the basics of snow and avalanche equipment. Belgrade Community Library. A raffle and pizza will be included!
Monday, December 12, 5-8 p.m. @MAP Brewing, Movie Night.
Tuesday, December 13, 6 p.m., Avalanche Awareness + Beacons at Story Mill Park. Free.
The Friends of the Avalanche Center are hosting the Powder Blast Fundraiser. Your donations support free and low-cost avalanche education, beacon checkers at trailheads, beacon parks, weather stations, and GNFAC programs! The Friends of GNFAC launched an online GoFundMe campaign. Please consider a donation, and we look forward to having an in-person event again in the future.