Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Forecast issued on Saturday, December 1st at 7:30 a.m. This Forecast is sponsored by Bridger Bowl and Stronghold Fabrication. This forecast does not apply to operating ski areas.
Overnight the mountains picked up 3-4” of new snow. At 5 a.m. it’s snowing lightly and temps are in the teens F. Wind are blowing 10-20 mph out of the W-NW. Today, snow gradually tapers off and skies will become partly cloudy by this afternoon. Temps warm to the upper teens to low 20s F and winds will remain light to moderate out of the W-NW. No significant accumulation is expected tonight into tomorrow.
New snow instabilities are main avalanche concern today. Three to four inches of low density snow won’t be enough to overload the generally strong snowpack (photo, video), however, it will be enough to elevate the avalanche danger.
Watch for areas of wind drifted snow on slopes loaded by west-northwest winds. Fresh wind slabs will be relatively small, but sensitive to human triggers. Watch for this problem below upper elevation ridgelines, gullies and rock outcrops.
A secondary problem will be loose dry avalanches or sluffs in steeper terrain. The new snow is low density and will move easily once initiated. Pay attention to this problem if you’re committing to steeper, high consequence terrain. Small slides can have severe consequences, especially in a shallow early season snowpack (video).
New snow and wind make human triggered avalanches possible on wind loaded slopes which have MODERATE avalanche danger. Non-wind loaded slopes have a LOW avalanche danger.
The Lionhead area has the weakest snowpack in our forecast region. The bottom half of the pack consists of weak sugary facets (photo, video). The four inches that fell last night totaled .4” of SWE, which won’t be enough to create widespread instability, but will put the snowpack on edge. The most unstable slopes will be those that received recent wind loading. Watch for signs of instability such as cracking/collapsing and stack the deck in your favor by keeping slope angles lower than 30 degrees.
Today, human triggered avalanche are likely on wind loaded slopes which have a CONSIDERABLE avalanche danger. Non-wind loaded slopes have a MODERATE avalanche danger.
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.
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).
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
IDAHO
Today! Klim Winter Kick-Off and avalanche awareness, Rigby, Idaho
BOZEMAN
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 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.