Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Forecast issued on Tuesday, December 4th at 6:45 a.m. This forecast is sponsored by Mystery Ranch and Highline Partners and does not apply to operating ski areas.
Yesterday, the mountains from Big Sky to West Yellowstone and Cooke City received 2-3” of new snow and light westerly wind. This morning skies are clear, temperatures are in the single digits to low teens and winds are blowing from the west at 15-30 mph. Today temperatures will rise into the 20s and drop to near zero tonight with moderate westerly wind. High pressure will block further snowfall through the weekend and bring cold, dry and sunny days.
Three inches of new snow and westerly winds in Lionhead will keep the potential for avalanches alive. Alex visited this area a week ago and concluded the snowpack is the weakest in our entire forecast area. At least a foot of weak, sugary snow underlies the 2-foot deep snowpack (photo, video). Step off your snowmobile and you’ll easily hit the ground since the snowpack is not supportable. Wind last night and today will load slopes so be extra aware of cracking or collapsing since these are signs that the snowpack is unstable and ready to avalanche. For today, avalanches remain possible on all slopes and the danger is rated MODERATE.
Today’s avalanche danger will center on wind-loaded slopes across the Bridger, Madison, and Gallatin Ranges, and also Cooke City. The last couple days have been eerily calm and the powder snow remained undisturbed. That changed last night. At the ridgelines wind speeds are gusting to 30 mph from the west while lower elevation sites are reading 20 mph from the east. In other words, swirly. Windblown snow will drift and load slopes at many elevations and aspects. Eric and Alex backed off Saddle Peak on Friday when they encountered wind slabs, a situation that will be similar today (video, photo, photo).
In general the snowpack is stable and lacks widespread weak layers. Many loose snow avalanches and a few wind slabs were reported (avalanche activity list) but no deeper layers were involved. Alex toured into the northern Bridger Range on Sunday and titled his video “Small avalanches, low danger” to illustrate the general stability he found.
For today, the powdery snow at the surface will be blown into drifts creating a MODERATE avalanche danger on all wind-loaded slopes and a LOW danger elsewhere.
If you get out and have any avalanche or snowpack observations to share, contact us via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
New this season, we added hyperlinks to the Weather and Avalanche Log and a new Menu item <Avalanches and SnowPits> with information on avalanche activity and incidents.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
BOZEMAN
TOMORROW, December 5, 1-hr Avalanche Awareness, 6-7 p.m. at REI, Bozeman
December 6, 1-hr Avalanche Awareness and Beacon Practice, 6:30-8 p.m. at Story Mill Park
December 7 and 9, Beacon Park for the Bozeman Ice Fest, Grotto Falls parking lot, Hyalite Canyon, 10 a.m. to 2 p.m.
December 11 and 12, Snowmobile Intro to Avalanches w/Field, Holiday Inn, West Yellowstone; more info here
December 12, 1-hr Avalanche Awareness for Snowmobilers, 6-7 p.m. at Yellowstone Motorsports, Bozeman
December 13, 1-hr Avalanche Awareness, 6-7 p.m. at Play It Again Sports, Bozeman
HELENA
December 12, 1-hr Avalanche Awareness, 6-7 p.m. at The Basecamp, Helena
COOKE CITY
Every Friday and Saturday, Rescue Training and Snowpack Update. Friday 6:30-7:30 p.m at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.
Check out our new “Avalanches and Snowpits” menu item where we list all the reported avalanche activity.