Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Sunday, March 25th at 7:00 a.m. Today’s advisory is sponsored by Grizzly Outfitters in partnership with The Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
Heavy snowfall yesterday dropped 8-11” of snow near Bozeman and Big Sky, and 2-5” near West Yellowstone and Cooke City. Yesterday, wind was south-southwest at 20-30 mph with gusts of 40-50 mph. Today, wind direction is variable at 5-15 mph. Temperatures are teens F this morning and will be in the 20s to low 30s F today. Little snow is expected today under mostly cloudy skies. Light snow showers tonight will dust the mountains with 2-4” of new snow by morning.
The storm yesterday favored the mountains near Bozeman and Big sky with 8-11” of snow equal to 0.7 - 1.2” of snow water equivalent (SWE). Strong south-southwest wind drifted the new snow into wind slabs that are easy to trigger today. These wind slabs are located near ridgelines as well as across mid-slope rollovers and along the bottom of cliffs.
Yesterday, skiers triggered avalanches in Beehive Basin and reported snow easily sliding on buried crusts (photo, photo). I was skiing nearby and found the potential for similar, unstable conditions (video). Eric was in Tepee Basin and found 8-10” of new snow and strong wind created unstable conditions on wind loaded slopes (video). Skiers in the northern Bridger Range saw a recent natural avalanche and fresh wind slabs forming in the afternoon. Today, wind loaded slopes deserve extra caution and should be avoided.
On non-wind loaded slopes, wet or dry loose avalanches are possible and can run long distances on firm crusts underneath. Below recent snow the snowpack is generally stable and deeper avalanches are not likely. Doug was in Bacon Rind yesterday and found a stable snowpack, but warned of quick changes that take place during long and sunny spring days (video). Brief glimpses of sunshine today can make wet loose avalanches easy to trigger or release naturally (video). Thorough and continuous snowpack and terrain assessment is essential.
New snow and strong wind yesterday make avalanches easy to trigger on wind loaded slopes, and possible on all steep slopes. Avalanche danger is CONSIDERABLE on wind loaded slopes and MODERATE otherwise.
The mountains near West Yellowstone and Cooke City got 2-5” of new snow equal to .2-.4” of SWE. This new snow was drifted into fresh wind slabs by strong south-southwest wind yesterday. Today, wind slabs are possible to trigger and wind loaded slopes deserve caution. Skiers near Cooke City have noted recent natural wind slabs over the last week (photo, photo), and they have reported the new snow easily sliding on recently buried, firm crusts. Dry or wet loose avalanches of recent snow are possible to trigger on steep slopes and can run long distances with a lot of volume. Recent snow and wind make avalanches possible today, and avalanche danger is rated MODERATE.
If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Cornice Fall, Centennial Mountains, ID
On Tuesday, March 20, a snowmobiler walked to edge of the ridge and broke a cornice. He tumbled to the bottom and was injured and air evacuated out (photo). A report of the accident is HERE.
Send us your observations on Instagram! #gnfacobs
Posting your snowpack and avalanche observations on Instagram (#gnfacobs) is a great way to share information with us and everyone else this spring.
Cooke City is buried with snow this winter. Sam Wilson of the Billings Gazette wrote an article on the potentially record busting season (article).