Regional Conditions for Southern Madison

Natural wet slabs were widespread on Fan Mtn. near Big Sky during the week of 5/13-5/16. Photo: E. Mullen

Natural wet slabs were widespread on Fan Mtn. near Big Sky during the week of 5/13-5/16. Photo: E. Mullen

Natural wet slabs were widespread on Fan Mtn. near Big Sky during the week of 5/13-5/16. Photo: E. Mullen

Natural wet slabs were widespread on Fan Mtn. near Big Sky during the week of 5/13-5/16. Photo taken 5/16: B. Rycenga

This natural wet slab slid early this week, Monday (5/13) or early Tuesday (5/14), near Beehive Peak. This photo was taken 0745 Tuesday morning. Photo: @cfirer

This natural wet slab slid early this week, Monday (5/13) or early Tuesday (5/14). Photo: @wallace_casper

Debris from a wet slab that released naturally Tuesday evening on saddle Peak. Debris ran very far into the runout compared to similar sized dry slabs that often occur on this path. "South side of 1/4 Saddle slid sometime last night. Looks like cornice drop then step down to near ground. Hi yesterday at Alpine was 62." -R. Elliott/BBSP

This wet slab released naturally Tuesday evening on saddle Peak. "South side of 1/4 Saddle slid sometime last night. Looks like cornice drop then step down to near ground. Hi yesterday at Alpine was 62." -R. Elliott/BBSP

"South side of the Glide Plane released as a glide avalanche last evening (May 12th) sometime around 6 pm according to source. Bed surface was ground in starting zone of wet clay soil sparsely covered in long grass.  Debris chunks, some snowmobile sized, rode up on surface and slid approx. 200 vert.  Debris could have bumped a tower on the old Alpine lift if it still lived there. Last freeze was 6 am on the 10th of May.  The high temperature on the 12th was 59 degrees at 4 pm." Photo and observations: BBSP

"South side of the Glide Plane released as a glide avalanche last evening (May 12th) sometime around 6 pm according to source. Bed surface was ground in starting zone of wet clay soil sparsely covered in long grass.  Debris chunks, some snowmobile sized, rode up on surface and slid approx. 200 vert.  Debris could have bumped a tower on the old Alpine lift if it still lived there. Last freeze was 6 am on the 10th of May.  The high temperature on the 12th was 59 degrees at 4 pm." Photo and observartions: BBSP

Skiers found fresh wind slabs that were easily triggered on Saturday 4/27 near Beehive Basin in the northern Madison Range. Photo: E. Birkeland

Spring Sled Fest is May 18th! DJ, Free BBQ, Raffle. All proceeds go to the Friends of the Avalanche Center. More event details here: https://www.facebook.com/events/2290792671007553/ Thanks to Mark Christensen @markass406 and Nick Donovan @skidooin_it for organizing the event.

Skiers easily triggered loose snow avalanches of the 3-5” of new snow. This morning (4/27) on the Bridger Ridge. Photo: @smooneyski

Skiers easily triggered loose snow avalanches of the 3-5” of new snow. This morning (4/27) on the Bridger Ridge. Photo: @smooneyski

Link to donate to the Friends of GNFAC: https://www.givebiggv.org/organizations/friends-of-the-gallatin-national-forest-avalanche-center

Debris from an older wet loose slide observed 4/20/19. Estimated to be a week old. Photo: G. Antonioli

Observed 4/20/19. Crown estimated 3-5' deep. Above freezing temperatures, sunshine and rain created a wet and weak snowpack. Photo: G. Antonioli

Observed 4/20/19. Crown estimated 3-5' deep. Above freezing temperatures, sunshine and rain created a wet and weak snowpack. Photo: G. Antonioli

From e-mail on 4/11/19: "We found reactive storm slabs and touchy windslabs near ridgelines. We kicked off a small windslab in 4th of July from the top of the couloir. Attached is a photo of the crown to give you a depth perspective. It was about 6 feet across and 3-4 inches deep."

Below 3-5" of new snow there is a supportable frozen crust on top of a wet snowpack on most slopes. Avalanches are mostly confined to the new snow on top of this crust (wet loose, dry loose, wind slabs). However, where the snowpack did not freeze below the new snow, or when this crust melts, deeper wet slides are possible. Photo: GNFAC

Snowmobile-triggered slide near Fairy Lake on Saturday (3/30). New snow was drifted into small wind slabs that may remain reactive in isolated areas.  Photo: P. Cronin

A snowbiker was partially buried in a slide on the west side of Sage Peak in the southern Madison Range. The slide occurred on a southwest facing slope at 8,700 ft. and failed on weak snow near the ground. The wet slab avalanche was triggered as the biker was side-hilling across the slope. He was caught, carried and buried to his chest, but fortunately escaped unharmed. Photo: D. Talbert 

Outside Cooke City up Zimmer Creek, a skier spotted this cornice fall which triggered a small pocket down low. Photo: F. Madsen

Many wet loose and wet slab avalanches were seen near Zimmer Creek (north of Cooke City) on south and east aspects. Temperatures were warm at 10,000 feet. Photo: F. Madsen

This photo near Lionhead, is indicative of the wet loose avalanches we are seeing on many low elevation, south facing slopes throughout our advisory area. Daytime temperatures near 50F will make avalanches like this more frequent and widespread in the coming days.

A snowmobiler saw this recent activity on Saturday 3/9/19 on Cedar Mountain near Big Sky.

This slide was triggered on a steep (40 deg) southeast facing slope at Round Lake outside Cooke City. It failed 8" deep on a layer of graupel and small facets. An adjacent hill slid at the same depth beforehand. This layer is not on most slopes, but as this slide shows it is on some. Doug was in the area and dug a pit in the crown soon after it was triggered. Photo: J. Fritz

This slide on the NE face of Blackmore was triggered by the second skier. It was 8-12" deep and 100' wide and likely failed on small faceted crystals underneath the new snow. No one was caught. Going one at a time was good travel behavior that can save our lives when things go wrong.

Two avalanche on the south face of Cone Mountain, southern Madison Range. Observed on March 4th, 2019, likely occurred several days earlier. Photo: B. Elkin.

An avalanche on an east/northeast aspect of White Peak in Upper Tepee Basin, southern Madison Range. Observed on March 4th, 2019, likely occurred several days earlier. Photo: B. Elkin.

Riders saw this avalanche (center of photo) on Saturday (3/2) just east of Sage Peak. Photo: P. Honsinger

A snowmobiler sent in this photo of multiple natural avalanches near Woodward Mtn. He also reported large avalanches near Pika Point and Skyline Ridge that failed at the ground. Photo: P. Honsinger

A snowmobiler triggered this slide on the afternoon of 3/2/19 behind Sage Peak in the southern Madison Range. Photo: J. Hillier

A snowmobiler triggered this slide on the afternoon of 3/2/19 behind Sage Peak in the southern Madison Range. Photo: J. Hillier

We received this report of an unusually large natural avalanche in the East Mill Creek drainage: " First time in 17 years we have had an avalanche come into our road. Natural, maybe from a point release that fractured new snow about 20 inches at the crown, propagated 50 yards, ran about 300 feet without stepping down, leaving about 5 foot deep debris. A new 2 inches is covering the debris that likely went during this afternoons warming."  Photo and comments: L. Watson

This avalanche failed on the ground up on Buck Ridge near the First Yellowmule. It was human-triggered, but nobody was caught or buried. Photo: N. James

This avalanche failed on the ground up on Buck Ridge near the First Yellowmule. It was human-triggered, but nobody was caught or buried. Photo: N. James

Snowmobile - triggered avalanche in the McAtee Basin area near Buck Ridge. The avalanche was triggered unintentionally from the runout zone and propagated all the way up to the ridge above the riders. Luckily, nobody was caught or buried. Photo: J. Stoner