Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Saturday, March 24th at 7:00 a.m. Today’s advisory is sponsored by Yellowstone Club Community Foundation and Montana Ale Works. This advisory does not apply to operating ski areas.
Since yesterday, the mountains near West Yellowstone and Cooke City got 1-3” of new snow with zero elsewhere. Temperatures this morning are mid to high 20s F and will remain mostly below freezing today. Overnight, wind was south-southwest at 15-30 mph with gusts of 40-60 mph. Today, wind will be west-southwest at 20-30 mph. A quick and heavy shot of snow this morning will favor the mountains near Big Sky and Bozeman with 5-8”. The mountains near West Yellowstone and Cooke City will get 2-4”.
Stability will decrease rapidly with heavy snowfall and strong wind this morning. Yesterday morning, Big Sky ski patrol easily triggered widespread 8-12” deep wind slabs that ran full track with a lot of volume. I was on Buck Ridge yesterday and saw light to moderate wind drifting 6-8” of new snow into unstable slabs (video). Skiers near Cooke City noted natural wind slabs the last two days (photo, photo), and on Wednesday a skier in Hyalite triggered a potentially dangerous wind slab (video). Today, wind slabs will grow larger and are easy to trigger. On non-wind loaded slopes, new snow will easily slide on firm old snow surfaces.
Cold temperatures, cloud cover and wind make wet snow avalanches unlikely this morning. If sun shines this afternoon, wet loose avalanches of new snow are possible (video). On Thursday, ice climbers in Hyalite witnessed a large wet loose avalanche over a popular climb, which would be a bad place to be caught (video).
Cornices along ridgelines are massive and should be kept a far distance from. On Tuesday, a rider in the Centennial Range broke a cornice, fell 600’ and was injured (photo). Below the recent snow, the snowpack is mostly stable and deeper slides are not likely.
With rapidly changing stability today the snowpack may seem complex, but your travel plans don’t have to be. Avoid steep, wind loaded slopes and slopes steeper than 35 degrees. Be aware of potential wet loose avalanches in sunny, steep terrain above you. Conservative terrain selection is the best defense against avalanches today.
Today, human triggered avalanches are likely on wind loaded slopes and natural avalanches are possible. Avalanche danger is rated CONSIDERABLE on wind loaded slopes and MODERATE on non-wind loaded slopes
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).