Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Center’s early season avalanche information issued on Friday, November 25 at 7:30 a.m. Today’s bulletin is sponsored by Yellowstone Arctic Yamaha and Yamaha Motor Corp. We will update this information tomorrow morning.
No new snow has fallen in the last 24 hours, but winds have increased. Yesterday winds blew out of the northwest in the Bridger Range and out of the southwest everywhere else. Speeds ranged from 20-25 mph with gusts of 30, except in the Hyalite area where gusts got close to 60 mph. Today skies will become mostly sunny in the afternoon as a ridge of high pressure builds. Temperatures will rise into the mid 30s from the low 20s overnight.
Check out our new button that displays the previous week’s weather and avalanche activity:
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Yesterday morning 6-8” of new snow carpeted the mountains of southwest Montana. It was measured around 6% density (.5 SWE) which means it was light enough to get blown around, which it did. In the northern Bridger Range in Sacajewea Bowl a skier triggered a small wind slab (1’ deep x 30’ wide) in a couloir that broke 10’ above and swept him through a rock pinch (photo). He was luckily uninjured. Winds picked up last night and today these wind slabs will be thicker and primed to avalanche. Ridgetops and couloirs are where an unsuspecting skier (or hunter, or climber) to could trigger one of these slabs.
Under the new snow lies various layers of crusts and hard slabs with facets sandwiched in between. Avalanches could also break on these facets. Although the snowpack is less than 2 feet deep in most places (Cooke City being the exception) facets can allow avalanches to break wider than wind-slabs alone.
Wind and new snow create avalanches no matter the season. Our tactics of skiing one at a time and carrying rescue gear are also not season dependent. Make good decisions, plan for the worst and be careful out there. And most importantly, have fun.
We will update this bulletin tomorrow morning and issue daily advisories and danger ratings when we get more snow.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.
BOZEMAN
30 Nov. and 1 Dec., Introduction to Avalanches with Field Course, 7-9:30 p.m. at MSU Sub Ballroom B: Sign up HERE.
6 December, Avalanche Awareness, 6-7:30 p.m. at MSU with Backcountry Squatters Ski Club, SUB Procrastinator Theater.
7 December, Avalanche Awareness, 6-7:30 p.m. at REI.
15 December, Avalanche Awareness and Beacon Practice, 6-8 p.m. at Beall Park.
HELENA
8 December, Avalanche Awareness, 6-7:30 p.m. at The Basecamp.
WEST YELLOWSTONE
15 and 16 December, Snowmobile Introduction to Avalanches w/ Field Day, West Yellowstone Holiday Inn Conference Hotel. More info and sign up HERE.
COOKE CITY
TONIGHT AND TOMORROW; 2 Dec. and 3 Dec.; 9 Dec. and 10 Dec., Weekly rescue training and snowpack update, Cooke City Chamber of Commerce on Friday and field location TBA on Saturday.