Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 15th at 6:45 a.m. Today’s advisory is sponsored by Yellowstone Arctic Yamaha and Yamaha Motor Corp in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
Yesterday, under sunny skies mountain temperatures reached the upper 40s. Today will be sunny and warm with similar temperatures and increasing wind from the southwest. At the ridgelines it’s currently blowing 10-15 mph with gusts of 25 mph. Tonight will become partly cloudy and tomorrow there is a slight chance of a rain or snow shower.
WET AVALANCHES: Above freezing temperatures will increase the wet avalanche danger on slopes getting full sunshine. Rolling pinwheels are a sign the snow surface is losing cohesion and wet-loose avalanches may occur.
The mountains around Cooke City are still adjusting to the huge snowstorm that ended late Friday. Over 11 feet of snow totaling 11” of snow water equivalent (SWE) fell. This was the third largest 14 day SWE total in Fisher Creek’s history. Lucas Zukiewicz, SNOTEL guru at NRCS, made a graph outlining the historical record HERE. Slopes harboring weak snow either avalanched during the storm or will stabilize in the coming days and weeks from the crushing weight. The likelihood of triggering avalanches is decreasing, but given we had an Extreme danger 4 days ago I am still wary of slopes that were wind-loaded, which is most terrain above tree line. On Sunday, a snowmobiler triggered a large avalanche on the backside of Daisy Pass (aerial photo, runout, crown). Even though winds are calm, slopes that were heavily wind-loaded need extra time to stabilize. For today, the avalanche danger is rated CONSIDERABLE on slopes that were previously wind-loaded and MODERATE on all others.
Take a look at our video playlist and photo page for a tour of the avalanche activity, from the ground and the air.
Today’s winds may keep the wet snow avalanche danger from spiking. Yesterday, a sizeable wet loose avalanche was seen in Beehive Basin. In the Madison and Gallatin Ranges and Lionhead area near West Yellowstone a buried weak layer of facets or surface hoar (1.5-2’ deep) are becoming harder to trigger as are wind-loaded slopes (photo and video). Over the weekend avalanches near Big Sky, in Hyalite, and Tepee Basin as well as a partial burial in Taylor Fork on Saturday should not be far from our minds, even with a decreasing avalanche danger. Eric and I rode into Taylor Fork yesterday to look at the avalanche that buried a snowmobiler (photo). The story with photo and video links are at the end of the advisory. For today, given the buried weak layers and previous avalanche activity, the danger is rated MODERATE on all slopes since human triggered avalanches are possible.
In the Bridger Range a lack of fresh snow, no wind-loading and above freezing temperatures has created generally safe avalanche conditions. Today’s forecasted winds may keep wet avalanche activity to a minimum. On some slopes there is a thin layer of facets located mid-pack that are breaking in stability tests. This is not widespread but is worth looking for in a stability test since it’s our only concern. Avalanches are unlikely but not impossible and the danger is rated LOW on all slopes.
Eric will issue the next advisory tomorrow morning by 7:30 a.m.
Taylor Fork, Sunlight Basin Avalanche: On Sunday, a snowmobiler was partially buried in an avalanche that was triggered by another rider traversing above him (photo) as he filmed from the runout zone. A thick wind slab avalanched at the ground on depth hoar on a very steep (> 45°) northeast facing slope. The filmer dove for his sled and hung on as the avalanche hit. He was tumbled and his airbag deployed on its own (go figure). He was uninjured and lucky to be alive (photo). The person who triggered it rode to safety. The avalanche debris dumped onto flat terrain making 15’ piles of hard slab debris. The rider held onto his camera and shared his video. Eric and I also made a video and took some pictures (overview, debris).
Crazy Mountains Avalanche: On Sunday, a snowmobiler triggered a large avalanche up Trespass Creek in the Crazy Mountains (photo). Luckily, no one was caught.
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
February 17, 1-hr Avalanche Awareness, 6-7 p.m., Madison Valley Rural Fire Department Station 1.
Bozeman
February 17-19, 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.