Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on February 17th at 6:45 a.m. Today’s advisory is sponsored by Knoff Group Real Estate with Pure West and Bridger Bowl. This advisory does not apply to operating ski areas.
Since yesterday morning the mountains picked up 5-8” of new snow. At 5 a.m. temps are in the teens F and winds are blowing 15-30 mph out of the west with ridgetop gusts in Hyalite and Taylor Fork breaking 40 mph. Today, strong winds will continue as another storm system approaches from the north. The southern mountains will see 2-4” by this afternoon while the northern ranges will pick up 1-3”. Heavier snow impacts the area tonight. The mountains south of Bozeman will see an additional 5-8” by tomorrow morning while the mountains around Bozeman will see 3-5”. Highs today will warm into the upper teens to mid-20’s F and winds will continue to blow 15-35 mph out of the west-northwest.
New snow and wind loading are the main concern across the advisory area. Over the past three days, most mountain locations have picked up a foot or more of snow totaling 1-1.3” of snow water equivalent (SWE) (video, video). This new snow has been deposited on variety of old snow surfaces. On some slopes the new snow rests over a melt freeze crust, while on others it sits over a thin layer of facts that formed during the short dry spell earlier in the week (video). Either way, steep slopes will be touchy to human triggers today, primarily those that have been wind loaded. Winds are forecasted to remain moderate to strong throughout the day, which will increase the size and distribution of wind slabs. Pay attention to blowing and drifting snow and avoid being on or underneath slopes that appear to be heavily wind loaded (photo).
On non-wind loaded slopes, soft slabs and dry loose avalanches (sluffs) are also possible (photo). In the mountains near West Yellowstone, there’s a slight chance for slides to fail on a layer of surface hoar buried 2-3’ deep. Yesterday, I rode in Cabin Creek in the southern Madison Range and found this layer in both my snowpits. Fortunately, it did not propagate in stability tests, which is a good indication it’s getting stronger. However, it’s still possible to trigger a slide on this layer in isolated areas.
Today, the combination of new snow and wind make human triggered avalanches likely on wind loaded slopes which have a CONSIDERABLE avalanche danger. Non-wind loaded slopes have a MODERATE avalanche danger.
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).
Upcoming Avalanche Education and Events
BOZEMAN
Feb. 28th, Know Before You Go avalanche awareness, 7:00 p.m. @ Procrastinator Theater, MSU
March 2nd and 3rd, SheJumps Companion Rescue Clinic, Info and Register HERE
March 2nd, Avalanche Awareness, 7-8:00 p.m., MAP Brewing Bozeman Split Fest
March 7th, Avalanche Awareness, 6-7:30 p.m. @ REI
DILLON
Feb. 24th and 25th, Snowmobile intro to avalanches w/ field course. More info: https://msuextension.org/conference/.
COOKE CITY
Every Friday and Saturday, Current Conditions Update and Avalanche Rescue, Friday 6:30-7:30 p.m. at The Soda Butte Lodge in February. Saturday anytime between 10-2 @ Round Lake.
What are SWE talking about? In Dashboard Talk: Episode 6 Alex and Doug discuss snow water equivalent and why avalanche forecasters care about it.