Regional Conditions for Centennial Range

From email:

"I wanted to make you aware of a snowmobile triggered slide in Lionhead today. Fortunately, I was not injured, was able to stay completely on top, climbed through the majority of the snow wash after seeing it begin to break, and relatively slowly slid down with the last of the moving snow while still on the machine. When I came to a stop, I stood up and was completely free of the snow. Our group is trained in avalanche safety, practiced beacon use prior to leaving town in the morning, were wearing avy gear, and were very fortunate that this ended up the way it did. 

A clear reminder that this can happen to any of us and to be careful out there."

Photo: Anonymous 

Snowmobiler triggered avalanche near Reas Peak on Sunday, 1/19/20. He was able to ride through it uphill. Photo: R. Gravatt

Snowmobiler triggered avalanche near Reas Peak on Sunday, 1/19/20. He was able to ride through it uphill. Photo: R. Gravatt

From obs: "I was on the west side of Pioneer Mtn digging a pit for YC Ski Patrol. I heard a few groups of snowmobiles cruising around the foothills of cedar. I turned and saw two snowmobilers cresting the ridge above the slide pictured as the debris was settling down. The sledders enjoyed the view for a few minutes before turning back the way they came and stumbled upon the slide they had unknowingly triggered. They skirted around the side of the crown and stopped for a few minutes. Based on the height of the rider off his sled, I would estimate the crown to be roughly 10’ at its max height. NE aspect below Cedar" Photo: J. Marcinko

With only 3" of new snow overnight, a cornice triggered a large avalanche at Lionhead early this morning. It broke 3 to 4 feet deep and propagated on a buried weak layer. This is the only stability test we need today, human triggered avalanches possible and the management strategy is to avoid steep slopes or be clear about your risk tolerance if you are poking into avalanche terrain. Photo: GNFAC

The snowpack in Lionhead is a respectable 6' deep. The facets near the ground are gaining strength and we were unable to get them to break in our tests. Stability is improving! Photo: GNFAC

February 1, King and Queen of the Ridge at Bridger Bowl (fundraiser). This is the Friends of the Avalanche Center’s second biggest fundraiser of the year. Come on out and help us raise money by hiking and skiing laps on the ridge. Prizes, camaraderie and a good time is guaranteed. Register with Bridger to hike in the event, and create a pledge page to raise funds with your Ridge laps.

We visited the avalanche that was triggered by a snowmobiler and partially buried 2 people on January 4th. The crown was 10 feet at the deepest part. Photo: GNFAC

We visited the avalanche that was triggered by a snowmobiler and partially buried 2 people on January 4th. The crown was 10 feet at the deepest part. Photo: GNFAC

 @carter.olson

A party of three skiers remote triggered avalanche with at least 6' crown off N face of Mt Porphry along rockband near summit on 12/29/19. They triggered it after tyhey had found "Three pits dug on NE face ascending Mt Porphry indicating increasing stability and no clean propagation. Approx 150-210 cm deep snowpack." Photo: G. Alsentzer

A natural avalanche observed on 12/26 from Lionhead Ridge. This slide likely broke during the storm on Christmas Eve. The avalanche is approximately 100 ft wide and on an east facing slope. It appears to have broken on a weak layer mid-pack.

Photo: GNFAC

We dug this snowpit in Denny Creek at the base of Lionhead Ridge near West Yellowstone on 12/22. An poor snowpack structure makes large avalanches possible to trigger. Photo: GNFAC

We toured up to about 7700 feet on a NE facing aspect in the N Madison, upon entering the bottom of the meadow we had several large collapses and then one very large collapse that propagated 100+ feet uphill while on lower angle terrain below the steeper terrain Of the meadow above. We dug a pit, we got an ECTP 10. The pit was 75 cm deep, we found basal facets with an ice crust on top and About 40cm of denser 3-4 finger snow above the ice crust. Photo: A. Palombo

Riders saw these recent slides on 12/15 near Carrot Basin. Photo: A. Wheeler

Riders saw these recent slides on 12/15 near Carrot Basin. Photo: A. Wheeler

Riders saw these recent slides on 12/15 near Carrot Basin. Photo: A. Wheeler

An old avalanche crown on Lionhead Ridge, taken 12/14. Photo: G. Antonioli

Skiers at Targhee Pass near West Yellowstone reported: "We got a few good collapses while skinning up through east-facing low angle meadows, and got some serious cracking and collapsing while stomping on fresh wind pillows just below ridgeline on a northeast-facing slope at about 8200'. We dug down at one of the cracks and found a 35cm thick F+ slab that had failed on a layer of 4-6mm depth hoar. Cracks propagated close to 100'..." Photo: A. Schauer

Riders reported multiple natural slab avalanches on N facing slopes. Note widespread crowns along slope in background. Photo: R. Rustigian

A snowmobiler triggered an avalanche (yellow pin) north of Crown Butte (the gray mountain at the top of the image). This zone is typically approached from Lulu Pass. His sled was partially buried, but the rider was not. Lots of new snow in the last 24 hours created a CONSIDERABLE avalanche danger.

This natural avalanche on the northeast side of Crown Butte near Daisy Pass (Cooke City) almost caught people below. Approximately 2 feet of snow has fallen with wind and the avalanche danger is rated CONSIDERABLE. Photo: B. Whittle

Photo taken 12/6 near Two Top, south of West Yellowstone.

From email: "South facing stuff was thinner than I expected and north and west facing was a lot better than I expected. South facing stuff was 59cm deep and we had multiple ECT-P 14’s between the facets at the bottom and the newer snow."

Photo: B. Radecky

This is a close-up of the angular Depth Hoar grains found near the ground in the mountains south of Big Sky to West Yellowstone. These are weak and cannot support a lot of snow weight. Avalanches will break near the ground on these. Photo: GNFAC

At the bottom of the snowpack is a thick layer of weak and sugary, faceted snow called Depth Hoar. These large grains do not bond well and form an unstable foundation of the snowpack. Avalanches will break at this layer. Photo: GNFAC

We put up the Taylor Fork weather station today (12/03) and it is churning out hourly data. Check it out here: https://www.mtavalanche.com/weather/stations/taylor-fork

We partnered with the Gallatin Valley Snowmobile Association to put in two new beacon checkers at the Taylor Fork and Buck Ridge trailheads. They are working great!

Thanks GVSA! Photo: GNFAC

We recognize that backcountry skiing can be daunting to approach. That’s why Ben Goertzen and the Friends of the Gallatin National Forest Avalanche Center have teamed up to help breakdown some of the most prominent barriers of entry to backcountry skiing through this campaign. One lucky winner will be given a complete backcountry skiing kit, a spot in an avalanche awareness course, and featured in a three part video series that ends with an excursion into the backcountry with professional skier and filmmaker, Ben Goertzen . These videos will be used by the Friends of GNFAC to help other aspiring backcountry skiers gain awareness, knowledge and start to breakdown their barriers to entry.

Click Here for More Details on How to Enter

Watch the Backcountry Barriers Launch Video: https://vimeo.com/376473804

These small crowns indicate that new snow may not bond well to the old snow surface. Photo: B. Fredlund

Sometime last week (11/20-11/22) these large avalanches occurred on heavily wind loaded northeast facing slopes in the Absaroka. The snowpack there is thin and faceted, similar to the southern ranges and mountains near West Yellowstone. Photo: B. VandenBos

Sometime last week (11/20-11/22) these large avalanches occurred on heavily wind loaded northeast facing slopes in the Absaroka. The snowpack there is thin and faceted, similar to the southern ranges and mountains near West Yellowstone. Photo: B. VandenBos

Strong winds found snow to transport on Saturday 11/23. Photo: B. VandenBos

From obs: "We took a tour up into the Maid today. A generally stable snowpack in the area, new snow seemed to bond well with the underneath crust layer. We did observe small pinwheels/rollers on steep pitches on southeast aspects, mostly due to the rocks heating up during the day. We also observed sluff buildup on aprons below the shadier and steep northern aspects." Photo: Tommy S.

A slab avalanche was spotted from the highway. This slope is to the north of Lionhead Ridge a few miles. Photo: B. VandenBos

As of 11/20/19 The mountains near Lionhead Ridge outside of West Yellowstone have thin snow cover. The snowpack is shallow (6-18"), and mostly weak and faceted. This will make dangerous avalanche conditions when it snows more. Photo: GNFAC

We skied into Lionhead Ridge on Wednesday, November 20th. The snowpack was shallow (6-18"), and mostly weak and faceted. This will make dangerous avalanche conditions when it snows more. Photo: GNFAC

"Lots of cracking up there this morning on fresh, mid elevation wind slabs"

Photo: B. Nobel

"While skinning up to the top of Powder Park lift at Bridger, we had roughly 15' cracks propagate on an E/SE aspect. A snowpit showed roughly 8" of wind slab above a few inches of facets, on top of last week's rain crust." November 11, 2019.

Photo: G. Lawrence