Regional Conditions for Southern Madison

From obs 4/9/21: "...we saw widespread natural wind slabs on N-NE eastern slopes in the Northern Absarokas (photo). Winds increased throughout the morning, and evidence of wind transport became more apparent at higher elevations. We found that on aspects unaffected by wind loading, the new snow layer was not cohesive and only saw minor sluffing." Photo: E. Schreier

Skiers had a collapse which made this crack on a south facing slope with a shallower, wet snowpack around 9,000' near Cooke City. Photo: J. Redfield

This wet slab was reported on 4/4/21 around 8,200' elevation in the Main Boulder drainage south of Big Timber, outside of our advisory area. It happened that day or very recently during extended above freezing temperatures. Photo: G. Smith

Two natural avalanches in Sunlight Basin occurred on a heavily wind-loaded slope. Also, note the very large cornice overhanging the slope. Avoid getting on top of or underneath these large overhangs of snow as they can break unpredictably. Photo: GNFAC

A small, natural avalanche in Sage Basin occurred on a heavily wind-loaded slope. Also, note the very large cornice overhanging the slope. Avoid getting on top of or underneath these large overhangs of snow as they can break unpredictably. Photo: GNFAC

Extreme winds on 3/28/21 transported snow that fell over the past week into fresh wind slabs. Photo: BSSP

From obs 3/28/21: "Saw this slope which frequently slides had been triggered on our way out last night [lower left in photo]. Slid to the ground but I expect it was mostly new snow as there is a larger old crown visible further uphill... I did see two other small pocket slides yesterday also in new snow on bed surfaces of older slides... General snowpack is getting very deep now but a thick junk layer remains at the ground everywhere I dug sleds out." Photo: J. Gerardi

From obs: "Deep slab avalanche in Blackmore Basin that appeared to break on the depth hoar near the bottom of the snowpack. It was on a wind loaded NE facing slope at approx. 9,500 and looked to break on a slope in the 35-40 degree range. The crown was about 8'-10' deep and 200' wide. It broke to the ground and ripped out several small trees." Photo: JR Mooney

From obs (3/27/21): "We were skinning up Pyramid Point from the East. as we approached 10,000 ft, we encountered a wind slab on an East Facing slope. it was about 1-2 inches where we encountered it, but it quickly propogated. the crown was 18-20 inches at its highest and about 150 feet wide. the debris ran for about 200 feet."

Ian and Dave stop to do a quick stability test as they hunt for a layer of weak snow 1-2 feet under the surface. Photo: GNFAC

From obs: "On our way up the summer trail route to Hyalite Peak our party of three remotely triggered a small avalanche from the skin track at around 9,600ft on a east facing aspect. The storm slab went about 4 inches deep and 150-200ft across a small roll over feature. We were about 150ft away when we triggered the slide." Photo: C. Kussmaul

On shady aspects, there is a layer of weak near-surface facets developing. These could become a problem if they get buried by new snow this weekend. On sunny aspects, the snow surface is getting wet and is becoming weak as it heats up in the afternoon.

In this photo, observe how both issues can occur on the same slope. 

Photo: GNFAC

Small wet slide on south facing slope low on Skyline Ridge. Observed 3/13/21. Likely broke in the previous couple of days.

Photo: GNFAC

Deep slab avalanche on Arden Peak at the back of Maid of the Mist basin in Hyalite. Probably broke between Feb 22 and Feb 28, 2021 Photo: GNFAC

Seen from near Ennis on 3/4/21. On Finger Mountain in the southern Madison Range. Photo: D. Frohman

Seen from near Ennis on 3/4/21. On Finger Mountain in the southern Madison Range. Photo: D. Frohman

We saw these recent wet loose avalanches on 3/6/21. SW aspect, 9,100'. They likely ran during above freezing temperatures between 3/3 and 3/5. Photo: GNFAC

From obs: "Small D1 avalanche on south-eastern aspect around 7800ft. Looks like solar released on older layer a day or two ago."

Photo: M. Mailly

From obs: "While touring above the canyon this morning, I noticed a very recent wet slide (would guess this incident occurred yesterday afternoon, March 4th). This was a skier triggered slide on a E aspect at an elevation of 7200. This slide was roughly 50 feet wide and ran about 50 feet, I estimated this crown to be 2-3 feet deep, slid all the way to the ground. This occurred below a steep roller."

Photo: T. Saulnier

"On the drive back we saw a large crown on the NW face of Big Horn peak..." (likely broke Sat or Sun, 2/27-28). Photo:  S. Jonas

Wet loose avalanches released in the warm sunshine on Tuesday, March 2nd. We expect many more in the coming days. Photo: S. Jonas

Sled Skiing in Third Yellow mule... after an air onto the slope the impact from landing resulted in a fracture and failure to / near the ground... in addition, a remote trigger occurred on adjacent slope... 200-300 ft to the skiers right. No body was caught in either slide. Skier that initiated failure was moving at high speed and was beyond slide path before majority of snow movement began. Photo: W. Miller

Sled Skiing in Third Yellow mule... after an air onto the slope the impact from landing resulted in a fracture and failure to / near the ground... in addition, a remote trigger occurred on adjacent slope... 200-300 ft to the skiers right. No body was caught in either slide. Skier that initiated failure was moving at high speed and was beyond slide path before majority of snow movement began. Photo: W. Miller

Sled Skiing in Third Yellow mule... after an air onto the slope the impact from landing resulted in a fracture and failure to / near the ground... in addition, a remote trigger occurred on adjacent slope... 200-300 ft to the skiers right. No body was caught in either slide. Photo: W. Miller

This avalanche was triggered on Sunday, 2/28, when a skier released another slide 2-300 feet away. It broke at the same time. No one was caught. This was in the Third Yellow Mule on Buck Ridge.  Photo: W. Miller

From obs: "With recent persistent winds the cornices are growing to impressive size. Noted a few natural cornice drops on the south 'rim' of Sage Basin." Photo: R. Larson

Riders triggered this slide on 2/28/21 near Red Canyon/Cabin Creek, north of West Yellowstone. Nobody caught or injured, but close call.

Riders triggered this slide on 2/28/21 near Red Canyon/Cabin Creek, north of West Yellowstone. Nobody caught or injured, but close call.

Riders triggered this slide on 2/28/21 near Red Canyon/Cabin Creek, north of West Yellowstone. Nobody caught or injured, but close call.

Riders triggered this slide on 2/28/21 near Red Canyon/Cabin Creek, north of West Yellowstone. Nobody caught or injured, but close call.

This recent avalanche failed on a heavily wind-loaded slope in Sage Basin along the ridgeline. It may have initiated as a cornice fall or a wind-slab, but it broke down to deeply buried facets. Even though it was a small slope, the slide had enough power to knock down a tree and piled debris deeply at the bottom of the slope. Photo: GNFAC

There was 6' of snow off the ridge in the Bridger Range on an east facing slope. The top 2 feet were recent wind drifting that broke clean in our stability test which indicated unstable conditions (ECTP18). We expect similar conditions and instability with wind-loaded slops throughout our forecast area. Photo: GNFAC

In the last 24 hours (2/28) 12" of low density powder and 40-50 mph west wind made it easy to trigger wind-drifted snow. Alex kicked these drifts which cracked and moved. We expect similar conditions and instability with wind-loaded slops throughout our forecast area. Photo: GNFAC

Natural avalanche in southern Madison Range. West facing. 9,000 ft. Look like recent wind-loaded snow. Observed 2/27/21. Photo: B. Nobel 

This small natural avalanche was seen by snowbikers in Beaver Creek in the southern Madison Range on 24 February. Photo: J. Stumne

From obs: “Triggered a large slide with a snowmobile. Went all the way to the ground. Crown seemed to range anywhere from maybe 3 ft to 10 ft. Large slabs of snow broke free and slid for about 100 yards.”

On 2/14/21 two splitboarders triggered this avalanche while skinning up the slope. One was caught, partially buried and critically injured. Photo: GNFAC

On 2/14/21 two splitboarders triggered this avalanche while skinning up the slope. One was caught, partially buried and critically injured. Photo: GNFAC

On 2/13/21 riders reported they triggered this avalanche, and remotely triggered two other slides. Nobody was injured. One partially buried.

On 2/13/21 riders reported they triggered this avalanche, and remotely triggered two other slides. Nobody was injured. One partially buried.