Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Sunday, February 23rd at 7:00 a.m. Today’s forecast is sponsored by Mystery Ranch and World Boards. This forecast does not apply to operating ski areas.
This morning there is no new snow, temperatures are teens to 20s F, and wind is westerly at 5-15 mph with gusts to 25 mph. Today will be partly sunny with temperatures reaching high 20s to low 30s F and west wind at 10-25 mph. Clouds increase this afternoon, and snow showers tonight will deliver 3-5” by morning with more snow through tomorrow.
The mountains last received snow four days ago. The snowpack has had time to adjust to the 4-6 feet of snow that fell since February 1st. This snow equaled 4.4-5.7” of snow water equivalent (SWE) which increased the season’s snowpack water content by 25-45% and caused widespread natural and human triggered avalanches. Triggering a deep slab avalanche is getting more difficult, but still possible. It has been five days since a deep slab avalanche broke on weak sugary snow near the base of the snowpack (photo, photo, photo), but we continue to get reports and take inventory of the recent carnage which warrants cautious travel.
Yesterday skiers near Emigrant peak in the Absarokas reported widespread old avalanche crowns (details and photos). Doug visited the huge avalanche near Maid of the Mist in Hyalite and said, “it is as big as it gets” (video, details and photos). He measured an alpha angle of 16 degrees, the lowest he has seen in North America. (A lower alpha angle means a farther runout distance (photo).
Yesterday was a sunny Saturday without a report of a human triggered or fresh natural avalanche. This is a good sign, but I’m cautious of the deep buried weak layers and wouldn’t center punch any steep mountains (e.g., Saddle Peak, Mt. Blackmore). Browse the avalanche activity on our website to see where recent avalanches occurred and avoid similar terrain. Recent activity was widespread across all aspects and elevations. Deep slab avalanches broke in and below narrow rocky chutes, and through sparsely treed hillsides. I mention these features because we (skiers) sometimes feel safer and better about stability here which is a false sense of security. Carefully consider stability and consequences of an avalanche on any slope steeper than 30 degrees.
Today it is possible to trigger avalanches many feet deep on weak sugary snow near the bottom of the snowpack. Choose routes that minimize exposure to avalanche terrain (video). Avalanche danger is MODERATE.
The southern Madison Range, southern Gallatin Range and Lionhead area near West Yellowstone received no snow in the last five days, and since February 1st got 3-4 feet of snow equal to 2.8-4.1” of SWE. The snowpack handled it better than the rest of the advisory area. The last reported avalanche was a week ago in Taylor Fork, triggered by a snowbiker and broke on sugary snow near the ground (details). Doug and Ian rode into Cabin Creek last Wednesday under clear skies and didn’t see any avalanches. They dug multiple pits and found a generally stable snowpack (video). Today avalanches are unlikely and danger is LOW.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.
Every Friday and Saturday, Snowpack Update and Rescue Training. Friday, 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.
March 4, 1-hr Avalanche Awareness. 6-7 p.m. at REI.
February 27-29, Bozeman Splitfest, More info and schedule here.
Last Saturday, three motorized snowbikers were caught in an avalanche in Colorado and two were killed. We are deeply saddened by this accident. You can read the preliminary accident report here. Please take the time to learn what we can from this and all accidents. Stay safe if you are getting into the mountains today.