Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Friday, March 10th at 6:45 a.m. Today’s advisory is sponsored by Javaman and Bridger Bowl. This advisory does not apply to operating ski areas.
Overnight the mountains around Cooke City picked up 8-10” of dense snow. The mountains around Big Sky including the southern Madison Range picked up 5-7” while the mountains around Bozeman and West Yellowstone squeezed out 1-2”. At 5 a.m. temperatures range from the upper 20s to low 30s F and winds are blowing 15-30 mph out of the W-SW with ridgetop gusts pushing 40 mph. This morning, the southern ranges could see 1-3” before snow tapers off by this afternoon. As the storm moves east, a ridge of high pressure will build over the area producing partly cloudy skies later in the day. No significant snowfall is expected tonight and tomorrow.
Although more snow fell overnight, the avalanche warning for mountains around Cooke City has expired. Since yesterday morning, Fisher Creek Snotel site picked up 8-10” of dense snow totaling 1.2” of SWE. This puts the three day total at 3.4” of (snow water equivalent).
Winds over the past 24 hours have decreased slightly, but are still blowing hard enough to transport snow. Today, natural and human triggered avalanches are likely on wind loaded slopes. This problem will be most widespread in upper elevation terrain leeward to W-SW winds. On non-wind loaded slopes, human triggered avalanches failing in the storm snow are likely.
Today, very dangerous avalanche conditions exist on wind loaded slopes which have a HIGH avalanche danger. Non-wind loaded slopes have a CONSIDERABLE avalanche danger.
Madison Range Gallatin Range Lionhead area near West Yellowstone
Overnight, the southern Madison Range picked up 6-7” of snow totaling .7” of SWE. The mountains around Big Sky received 4-5” totaling .4” of SWE. The storm came in warm and the new snow should be well bonded to the old snow surface. With that said, moderate to strong winds out of the W-SW are likely transporting snow and forming fresh wind slabs on leeward slopes (video photo). In addition to wind slabs, cornices are growing large and dangerous.
Yesterday, a snowbiker on the Lionhead Ridge outside of West Yellowstone had a close call when a large cornice broke under his bike. The rider was able to jump and land on the ridge, while his bike took a ride to the slope below. Doug and Alex showed up on scene only moments after the incident occurred. See Doug’s video and interview with the rider (video). Last week, a snowmobiler also feel off the Lionhead Ridge when a cornice broke under his sled. Give these large overhanging pieces of snow a wide berth above and below the ridgelines.
Today, human triggered avalanches are likely today on wind loaded slopes which have a CONSIDERABLE avalanche danger. Non-wind loaded slopes have a MODERATE avalanche danger.
Bridger RangeThe Bridger Range picked up 6-8” of snow Wednesday night. The snow came in with light wind and bonded well to the old snow surface. Winds picked up yesterday afternoon and a skier in the northern Bridgers observed wind loading near the ridgelines. They also observed point releases in the new snow that could potentially carry a skier or rider. Temperatures in the Bridgers this morning are at or above freezing which will make wind slabs that formed yesterday soft and stubborn. It will also turn the new snow into soft, mashed potatoes by this afternoon.
Today, avalanches are possible on wind loaded slopes and in steeper terrain. For this reason the avalanche danger is rated MODERATE in the Bridger Range.
Alex 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 (photo).
COOKE CITY
Today and tomorrow! UYSC 21st Annual Hog Roast. More info here. Free avalanche rescue practice on Saturday.