Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Thursday, February 23rd at 6:45 a.m. Today’s advisory is sponsored by Mystery Ranch and Yellowstone Club Community Foundation. This advisory does not apply to operating ski areas.
Since yesterday morning, the Bridger Range picked up 5-7” of new snow and the northern Gallatin Range (Hyalite) picked up 10” of new snow. The mountains around Big Sky received 3-5” while the southern ranges squeezed out 1-2”. This morning, light snow showers continue in the mountains around Bozeman and temperatures range from the single digits to low teens F. Winds are blowing 10-30 mph out of the N-NE. Today, highs will warm into the low teens F and winds will remain light to moderate out of the N-NE. Light snow will continue and the mountains should see an additional 1-3” by tomorrow morning. East winds typically do not produce heavy amounts of snow, so any accumulation over the next 24 hours will be light.
Wind loaded slopes are the main avalanche concern in the southern ranges. Earlier in the week, heavy snow and strong winds formed thick slabs on all aspects and elevations. On Tuesday, Doug and I rode in the Lionhead area near West Yellowstone and observed numerous natural avalanches in wind loaded terrain (photo, video, photo). Alex also observed heavy wind loading around Cooke City on Tuesday. Although winds have calmed over the past 24 hours, wind loaded slopes will remain sensitive to human triggers.
A secondary concern will be avalanches failing on a layer of facets buried 1-3 feet deep. This layer has been found in the mountains near West Yellowstone including the southern Madison Range. We have few reports of this layer around Cooke City, but I wouldn’t rule it out. As this weak layer struggles to adjust to the heavy load from the past 4-5 days, it still holds the potential to produce avalanches.
Today, it will be easiest to tip the scales and produce avalanches on wind loaded slopes which have a CONSIDERABLE avalanche danger. Non-wind loaded slopes have a MODERATE avalanche danger.
Bridger Range Northern Gallatin Range Northern Madison Range
For once, the northern ranges picked up more snow than the south. Since yesterday morning, Shower Falls Snotel site in the northern Gallatin Range is recording 10” of new snow totaling .8” of SWE. Brackett Creek Snotel site in the Bridgers is recording 7” of new snow with .5” of SWE, while the mountains around Big Sky are in the middle with 4-5” totaling .3” of SWE.
Yesterday, the Bridger Bowl Ski Patrol triggered small soft slab and loose snow avalanches in steep terrain. A skier up Mt. Blackmore also observed small natural avalanches off the east face. As winds continue to blow out of the N-NE today, loading patterns will be unusual. Keep an eye out for blowing and drifting snow and avoid all slopes that appear to be wind loaded.
While new snow instabilities are the main avalanche concern, a layer of facets buried 1.5-2’ feet exists in the mountains around Big Sky. We have not seen recent avalanche activity on this layer, but it should be looked for and assessed before jumping into avalanche terrain.
Today, human triggered avalanches are likely on wind loaded slopes which have a CONSIDERABLE avalanche danger. Non-wind loaded slopes have a MODERATE avalanche danger.
I will issue the next advisory tomorrow morning by 7:30 a.m.
Less People, More Fatalities, a new article by Doug Chabot on avalanche fatality trends in Montana.
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.
Beacon Training Park at Beall: Open and free to the public for avalanche beacon practice seven days a week from 9 a.m. to 8 p.m., southeast corner of Beall Park in Bozeman (photo).
COOKE CITY
Weekly rescue training and snowpack update, 6:30-7:30 p.m., Cooke City Super 8 on Friday, Lulu Pass Road for field location Saturday (Look for the yellow sign).
Bozeman
March 1, 1-hr Avalanche Awareness, 6-7p.m., REI Bozeman.
March 4, Pinhead Classic, Proceeds to benefit Friends of GNFAC. More info here.