Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Friday, February 17th at 6:45 a.m. Today’s advisory is sponsored by the Pinhead Classic and Spark R&D. This advisory does not apply to operating ski areas.
Overnight, a quick storm dropped 5” of snow in the southern Madison Range. The mountains around Big Sky, West Yellowstone and Cooke City picked up a trace to 1” while the mountains around Bozeman remained dry. This morning, temperatures range from the mid-teens to low 20s F and winds are blowing 15-35 out of the W-SW with ridgetop gusts pushing 40 mph. Today, temps will warm into the high 20s to low 30s F and winds will gradually decrease throughout the day. Another round of moisture impacts the southern ranges tonight. The mountains around Cooke City and West Yellowstone should see 2-3” by tomorrow morning.
The snowpack around Cooke City ranges from 6 to 10 feet deep. Persistent weak layers are not widespread and the pack has had time to adjust from the near record breaking snowstorm last week (photo page). Avalanche activity has been minimal the past few days; a clear indicator avalanches are becoming harder to trigger.
While human triggered slides are less likely today, they are still possible. If a slide is triggered, it has the potential to be large and dangerous. Be extra cautious in steep, rocky terrain where it may be easier to impact buried weak layers. Also, watch for and avoid recently wind loaded slopes.
Today, human triggered avalanches are possible and the avalanche danger is rated MODERATE.
Madison Range Southern Gallatin Range Lionhead area near West Yellowstone
Overnight, Carrot Basin Snotel site in the southern Madison Range picked up 5” of snow totaling .5” of SWE. This will improve riding conditions without significantly increasing the avalanche danger. This fresh snow will form a few wind slabs below leeward ridgelines, but these should be relatively small and easy to avoid.
Aside from wind loaded slopes, a layer of facets buried 1.5-2’ deep still exists. This layer is gaining strength, which is making avalanches harder to trigger. Both the wind slab and persistent weak layer problem are confined to slopes above 8,000 ft. In mid to low elevation terrain, the snowpack has been exposed to free moving water due to warm temps and rain. In these areas the snowpack will be mostly stable as temps hover at or below freezing.
Today, human triggered avalanches are possible (mainly in upper elevation terrain) and the avalanche danger is rated MODERATE.
Northern Gallatin Range Bridger RangeYesterday, while hiking up the Blackmore trail in a T-shirts, we were passed by a mountain biker. This is a clear sign conditions are changing. Above average temperatures, strong winds and the lack of snow have created highly variable conditions. On the upper mountain yesterday, we didn’t find a single slope untouched by warm temps, sun and wind. Needless to say, skiing wasn’t great. On the flip side, we both felt comfortable venturing into avalanche terrain and agreed spring like conditions are helping stability.
With a strong refreeze overnight, human triggered avalanches are unlikely today. It will be worth paying attention to previously wind loaded slopes near upper elevation ridgelines. We did observe one recent slab avalanche on the north face of Mt Blackmore triggered by a cornice drop (photo). This is a good reminder that Low danger does not mean NO danger.
Today, generally safe avalanche conditions exist and the avalanche danger is rated LOW.
I will issue the next advisory tomorrow morning by 7:30 a.m.
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.
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).
ENNIS
Tonight, 1-hr Avalanche Awareness, 6-7 p.m., Madison Valley Rural Fire Department Station 1.
Bozeman
Today through the 19th, Bozeman Split Fest, rescue clinic/avy conditions talk on Friday. More info here.
March 4, Pinhead Classic, Proceeds to benefit Friends of GNFAC. More info here.