Avalanche Activity

We rode to the Taylor Fork weather station (near Pika Point on the rim of Sunlight Basin) and noticed a few slides along the way. At the weather station we could see that the north end of the basin natural avalanched: the slopes from where the cornices end in Sunlight Basin past Pika Point. It broke up to 2.5 feet deep on an old layer of facets and surface hoar. The slide was R2 D2, 3-400 feet vertical and at least 750 feet wide. It was a large Hard Slab. We spent time at the crown digging, making a movie and getting cold. No surprises, just great to see a real avalanche. We also saw smaller slides looking west from the station, close by. Afterward, we rode to the Sage/Carrot divide in deep snow; hero riding. Skyline Ridge was obscured in clouds.

On the drive back to Bozeman we could see many slides on road cuts and on slopes across the river; low elevation avalanches that we don’t get to see often.

The avalanche recorded in this form is the one in Sunlight Basin that we made the movie about.

On 2/4/23 we toured up the ridge between Going Home Chute and Tyler's (below prayer flags). We saw evidence of a large avalanche that broke during the avalanche warning last weekend in Going Home Chute, R3-D2.5 (see photos). It appeared to have run to the end of the runout zone and tipped over small trees.

From IG "Natural slide on southwest facing slope along Jack Creek Road in Moonlight Basin"

Took a drive up and around the Yellowstone Club and saw this slide today. I think that is Cedar Mt with Pioneer Ridge in front and to the left. Stay safe out there.

I was skinning up the ramp on Friday when I thought I heard a jet flying over in the clouds, but the sound stopped instantly. I assumed that I heard an avalanche, but was solo on the ramp and had no desire to go that way for a better look.  It was snowing and foggy. Today a friend said she could see a crown on the north side of Wolverine bowl that appeared to be 4 feet. With all that water, I thought something would go deeper, eh?

There were numerous debris piles, point releases, and crowns on the north face of Elephant and the northeast face of Blackmore this morning.  Most of them appeared to have run during the storm (1/27) and had been covered by at least 6 inches of new snow. 

We rode through 1st, 2nd, and 3rd Yellowmule. Measured 13” of new snow with 0.6” SWE in 1st Yellowmule at 10 am. This brought the two day snow total to approximately 20”. Snowed all day with varying intensity and there were strong west winds along the ridge. 

Visibility wasn’t great, but we saw most of the avalanche terrain in the Yellowmules. .....  saw a very small snowmobile triggered avalanche on a roadcut on the way out (6-12 inches deep, ~20 ft wide) that broke on facets in the thin snowpack. 

From IG:

2-3 feet of new snow was reported above Round Lake in Cooke City. Many natural avalanches were seen on S-SE slopes. From afar they look to be breaking on new-old snow interface.

Natural avy on SE aspect 8000 ft 35 to 40 degrees. Broke on new snow interface today. YNP next to Silver Falls.  Also several slides in gully below falls.  

Made it out past round lake around 11am this morning - dug multiple hand pits  above 9400' to gauge new snow depth - 40-50 cm new snow from this storm, very light, over the hood riding!  Minimal wind below alpine, upper 20cm new snow collapsed easily in hand pits, very little cohesion in the new snow.

Observed several smaller avalanches, all in new snow, undetermined whether natural or ridder triggered, attached photo of the only slide I could get an alright photo of, vis was limited. 

A skier triggered a slide about 20-30 yards wide and 2-4ft thick. 

On January 28 we rode along Buck Ridge... Visibility wasn’t great, but we saw most of the avalanche terrain in the Yellowmules. Saw one avalanche along the 2nd Yellowmule headwall that broke 100-150 ft wide just under the new snow (maybe 1-2 ft deep, it was hard to tell)....

An ice climber across the valley observed a large natural avalanche running over Silken Falls ice climb on the east side of the Main Fork. Wind was blowing and moving snow all day. This gully gets wind-loaded and was the site of a fatal avalanche in 2009.

Had some cracking, collapsing of wind drifts up high on the ridge today and few DLs running into Wolverine.

Winds were swirling, and coming from the south when I was skiing, but obviously the storm pattern is moving from the north.

Super wind scoured slopes from yesterday not bonding well in other places.

From Obs: "Dug on a sheltered N aspect at 9,000 feet below Alex Lowe Peak. Performed an ECT with results of ECTN 12 at 30cm deep and ECTP 21 near the ground.  

We also observed widespread sluffing of the new, low-density snow throughout the day and increasing wind transport in the afternoon."

Observed two recent natural avalanches on 1/25/23 that broke 1-2 feet deep, presumably on a surface hoar layer. There was a couple of inches of snow on each of these slides, so I would place them between three and five days old. The slides were R1-D1.5 in size - 75-100' wide, 1-2' deep, and 100' vertical fall. Photo: GNFAC

Skiers near Mt. Blackmore noted easy-to-trigger loose snow avalanches sliding up to 8" deep. 

Beartooth Powder Guides reported remote triggering a small wind slab on the SH layer and a small natural in the lower part of the Bowl that also likely slid on the fresh SH 40’ wide 4” thick. East aspect 9900’.

From Big Sky Ski Patrol 1/21/23: "skier triggered a surface wind slab in Wyoming Bowl that broke 8-12” deep. It propagated to an estimated 150’ wide- SS, R1/D1.5... The slide was small, no one was hurt, and the avalanche was reported (which we appreciate), with no further public involvement other than the trigger."

Bad quality but a D2, R3 natural in Flanders cirque. Looked like it was just the new snow, but hard to say.... on a NW aspect around 9,500 feet

Observed this cornice fall triggered slide morning of 1/19/23. It was not there the previous morning which was sunny and clear. Photo: GNFAC

Natural soft slab release likely in the last 36 hours. Seen from in-bounds at the Yellowstone Club. Avalanche location at 45.2116512 N 111.47811 W at the headwaters of Muddy Creek. 

I dug one pit at 8200’ NE aspect in Yale ECTX. Kevin was a little lower and around on the east side of Sawtell, he felt a big wumph. He didn’t confirm what layer, but this is probably your buried SH.

Today we toured up Storm Castle Ridge with hopes of skiing the 19th Street Couloir. On the approach we were able to trigger small (2-4") wind slabs on most lee aspects, these slides ran fast and far for their size. We dug a pit at 9200' on a North aspect and we're able to identify the surface hoar but had no results on our ECT.  With 2 spotters I dug an ECT 10m below the top of the 19th Street Couloir and got and ECTP12@ 35cm below the surface. The slab was 35cm thick, pencil hardness and failed on faceted snow; the buried surface hoar found in most other pits was not present. We bailed to the opposite side of the ridge and enjoyed some wonderful burn skiing. 

Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown. 

A snowboarder triggered two shallow avalanches (estimated 4-6 inches deep) on Saddle Peak in the new snow. The slide was as the snowboarder dropped off "Quarter Saddle" and a second pocket propagated above him as he traversed out of the first slide. The snowboarder wasn’t caught and the debris mostly stopped short of the main cliff with a little pile dropping off into the going home chute.

Another slide was seen from the highway in Argentina Bowl. This slide appears to be a shallow soft slab that ~50 ft wide and ran ~500 vertical ft.

Dave and Doug rode around and saw multiple natural and 1 sledder triggered slide on Lionhead. Some were thin and just involved news snow and others were deeper and broke on the buried surface hoar layer.

Observed a point release that appeared to have stepped down. This occurred SE of the “rip curl” zone. We also noticed significant sun effect and a warming trend throughout the day. 1/17/23

East aspect, 10,300.  Estimated to be about 75' wide.  Likely occurred yesterday, Jan. 17th.  

Noted a couple of fresh slab avalanches out there today.  Both were on northerly aspects around 9300'.  Photo of one attached.

From obs: "Toured into Alex Lowe basin today and noticed lots of point release slides. Most started as spindrift in the cliff bands along the ridge and gained more snow as they fell into the aprons. Skied a north and south facing couloir, ski cut at the top of both runs and got the new snow to sluff most of the way down. Didn't encounter any cohesive slabs, just lots of sluff sliding down."

Dug a pit on the east side of Henderson at the ridgeline above Henderson Bench. ENE, 10,075' elev. ECTP19 x3 on a layer of surface hoar buried 60cm (2 feet) deep. HS 260cm....

There was also a more recent natural avalanche (less than a day old) on Miller Ridge. SS-N-R1-D1.5-O and probably broke on the surface hoar layer.

Skied on Henderson mountain the afternoon of 1/16. Wind was calm, snowfall was light and steady through the day with 3-4" of new snow.

Dug a pit on the east side of Henderson at the ridgeline above Henderson Bench. ENE, 10,075' elev. ECTP19 x3 on a layer of surface hoar buried 60cm (2 feet) deep. HS 260cm. There was an avalanche a few hundred feet north on an east-northeast facing slope below the ridge. It appeared to be snowbike triggered and 1-2+ days old. 150' wide and 250' vertical. HS-AMu-R2-D2-O. It appeared to have broke about 2' deep on that layer of surface hoar. (There was also a more recent natural avalanche (less than a day old) on Miller Ridge, slightly smaller. SS-N-R1-D1.5-O and probably broke on the surface hoar layer. Separate entry in avy log).

From Obs: "Ski cut sent a slide that failed on the known-to-be-reactive buried surface hoar layer . Avalanche broke around 12-14” deep, 100’ wide and ran around 100 yards. It was extremely sensitive.
We had skied a similar angle/aspect slope earlier and didn’t get any reactivity. Occurred around 9000’ on NW slope.~ 32 degrees. We did this 2 times on what we thought to be low angle slopes. ended up skiing down a low angle ridge line. The buried hoar isn’t everywhere but it’s touchy when found."

On January 16 observed an old cornice triggered avalanche on Miller Ridge that broke to the ground, appears to be many days or weeks old.

We observed a north-facing natural sluff turn into a reasonable slide release over the cliff bands from the ridge line between Miller and Wolverine today while skinning on the flat bench above the road out to Wolverine Peak today. I think it released right at Sunset peak. It may have started with a cornice release but was more like wind loading on the steep face. We also saw some minor cracking on north facing wind loaded roll overs above the bench. We opted to descend low-angle trees back to our sled and to go ski Henderson.

Started a small wind slab avalanche on an isolated rollover about 2/3 of the way down the face of elephant mountain yesterday (Thursday January 12th). Broke a few inches deep, about 8 feet wide, and ran less then 100 ft. 

From obs:

While skiing down 'Fat Maid' I triggered a shallow wind slab, after I was about 3/4ths of the way down the couloir. The slide broke to my left as I entered a wider section of the run, that holds a small perched bowl feature (which is what ripped out). The slide didn't propagate out into the main couloir, so the debris never impacted me. Even if it had, I don't think it would've been big enough to knock myself or any other skier off their feet. The slide was about 1/2 the width of the couloir and ran out to about 3/4ths of the apron's length (R2 D1?). The crown was 1-3" deep and maybe 30-40' wide. 

Four small avalanches triggered on SH/NSF.

From obs: "On a few small steeper rollers/micro terrain/logs we released 4 small avalanches on the layer closer to the surface. The biggest slide we triggered was maybe 10-15ft wide and 1ft deep."

From Facebook: High Mountain Adventures snowmobile rental reported one of their renters triggered a slide on the waterfalls (Mt Jefferson/Sawtelle).

Photo attached of a fresh natural avalanche, just south of Cooke City today.  It appears to have run last night or this morning.  (photographed at noon)

We saw 2 avalanches that looked to involve new snow. One was on Wolverine on the face and another was on Henderson Ridge under the radio hut. They did not propagate far and wind-loading may have been a factor on the Henderson Ridge slide.

Snowboarder triggered this slide on a rollover on East Republic. Reportedly ran 80' wide, 1-1.5' deep. No one was caught.

Rider-triggered avalanche reported near Lulu Pass. Limited details. Unknown if anyone was carried or buried. 

A rider triggered a small slide in First Yellowmule on Sunday. Broke 6 -8" deep, 60' wide, and ran 20'. North face, about 37 degrees steepness.

From email: "Remote triggered avalanche yesterday on west facing slope of lone mountain backcountry. Observed wind loaded Slope, shooting cracks then woomph, followed by a collapsing snow pack 20 feet ahead. Crown approximately 1.5 feet tall 15-20 feet wide."

A rider-triggered avalanche was reported from a slope near Chimney Rock on the north end of Henderson Mountain. Limited details. Unknown whether anyone was caught or buried. 

Skier unintentionally triggered and was caught in wind slab avalanche on the Y couloir in Sheep Creek Drainage. Skier was carried 10m before self arresting. The slide ran ~250m down and broke across the entire width of the couloir. There were no injuries and skied away. 

Location: 45.165, -111.35808 (onX) 

Elevation: ~9,200 feet

While riding a small NNE facing slope near the trail on Buck Ridge, a snowboarder triggered and followed a cornice slide that propagated approximately 75 feet and slid about 20' vertical. The one rider was caught and carried approx. 10' and ended up buried upright, waist deep with no injuries. 

From IG 1/7/23: "Natural slide in avalanche bowl up in fairy lake today."

While skiing back to our sleds we triggered a very small slide on a small, ~35º below treeline slope (SS-ASu-R1-D0.5). This was on a southerly aspect, at about 7,000 feet, 4-6” down on surface hoar, 15’ wide, 30’ vertical run. There was a very hard crust underneath the surface hoar. 

At 1:30 PM on Jan 6th a large avalanche poured over the cliffs on Saddle Peak, outside the boundaries of Bridger Bowl. Clouds obscured the starting zone. Multiple groups were in the runout zone, including a skier hitting a jump. One person was caught and buried up to his neck. He was able extricate himself and was unharmed. He did a beacon search at the toe of the debris. He estimated the debris was at least six feet deep.

We believe this was a natural avalanche that broke in the new and wind drifted snow which then broke into older snow. Bridger Bowl measured 6" of new snow with 0.75 inches of Snow Water Equivalent at the Alpine Wx. Station. The avalanche was estimated to be 2 feet deep, and measured on Google Earth to be 550 feet wide and 1700 feet long. 

Recent low density snow was drifted into 10” soft slab from west wind, north of Cooke City. Skier triggered intentional on test slope. 

Had seven sleds in a relatively small area on the south-facing side of Taylor mountain at about 10k ft.

Group noticed a substantial whumph after sitting for less than a minute.

At about 10 AM I was belaying my partner on the first pitch of Bobo Like in the Flanders drainage of Hyalite Canyon.  We heard a low rumble and a couple seconds later we were engulfed in snow that poured out of the the pitch 2 gully, and seemed to keep coming for about 5 seconds.  My partner, who was on lead, was lucky enough to be at the base of the vertical ice of p1, so the snow mostly went over his head.  I was off to the side and close to rock at the base and was engulfed in loose snow, but not buried or injured.  We continued up afterwards.  When I was at the top of the second pitch, belaying my partner up, another small loose snow avalanche came down as river of snow, passing me as I hugged the anchor, and washed over my partner while he was on the pitch.  We were fortunate to have both been in positions to handle these avalanches without incident or injury.  In retrospect, the clear day and blasting morning sun likely loosened the snow above the gully and funneled it all down onto us.  After the first avalanche, the sun must have kept moving onto new slopes above, releasing more snow.  Even with a moderate danger level in the avalanche report for the day, with natural avalanches unlikely, we happened to find ourselves in a very specific scenario, with morning sun and a dangerous terrain feature, that still put us at risk.  Hopefully we will use this experience to improve our assessment of risk, terrain, and evolving conditions in the future.

From FB message: “Near Sage Creek/Sage Mountain in carrot basin. This was a east facing, wind loaded slope. Snowmobile triggered below the rock line. No burials.”

Two natural avalanches in the Cabin Creek area.

From instagram: "Right off the trail at tepee creek just before the cabin. A natural slide about 2ft crown"

From email: "I came across this older avalanche yesterday when I was guiding a group in the Kirkwood area, it’s an area in the Cabin Creek drainage. It looked to be an older natural slide probably just after the last storm cycle a few days to almost a week ago now. North, North East Aspect. Approximately 39 degree slope (Because of a creek with open water just below the slide, I couldn’t get close enough to accurately measure the slope)". 

Small snowmobile triggered slide (~1ft deep and ~20x20 ft) at the head of Muddy Creek (NE Aspect, 9400 ft) off Buck Ridge. Looks like it was likely triggered on Sunday (Jan 1st) in a shallow spot near rocks.

From BBSP: "The recent storm snow in the bowl south of Quarter Saddle avalanched overnight, from what appeared to be a cornice drop.  The debris stopped shy of the second cliff band."

Riding below Lionhead Ridge on 1/2, we observed several relatively small slab avalanches that failed below the weekend's snow. As well as several loose snow avalanches in steep terrain. 

From obs: "A small, snowboarder-triggered avalanche from 12/31 on a southeast-facing slope at 9,000 feet broke on the 30cm layer and stepped down to the 40cm layer. The snowboarder was briefly caught in the sliding snow but maintained his footing as the snow washed past him."

skied both NE, S and SW aspect lines in Sheep Creek Basin. No signs of wind loading where we traveled, up to 9600’ at the saddle between Sunset and Miller Mountain. There were light winds (M gusts). 8-10” of new low density snow.

Dug a pit on a SW aspect, 8480’:

160cm deep

CT22Q2 Down 40, EctN 25 down 40

ECTP28 down 85

Pole probing confirmed the presence of the top persistent grain layer throughout the landscape, although the associated crust was not widespread. 

We also experienced a Whumpf at 45.03667, -109.96733 On a SW slope, 9000’ in a shallow area (125cm depth). 

On the way back to Lionshead.  Came upon this recent avalanche.  Rushed up to the group of 4 guys.  They were fine, not the guys who set it off.  The group of 6 we passed going there set it off.  The group of 4 said they saw these guys ... all on the hill at same time, stuck and climbing around the stuck guy.  All were okay but I hear one guy was shaken up. 4-5ft deep at break by 200-300ft wide, ran 400+ft.

On December 31, 2022 a snowmobiler was killed in a very large avalanche north of Cooke City, MT. The avalanche occurred near Daisy Pass on Crown Butte on a southeast facing slope at 9,800’. Two brothers (age 17 and 21) from Washington were snowmobiling uphill on adjacent slopes. The older brother was climbing a steeper slope and triggered the avalanche 100-200’ below the top. He was carried 600 vertical feet and buried 5 feet deep. The buried rider was wearing an airbag pack that was not deployed. Both riders had shovels and probes. They were not wearing avalanche beacons. A nearby group of riders rode up to the slide within minutes after it happened, saw a buried snowmobile and began to search for the rider. One rider from that group went into Cooke City to alert Search and Rescue. The buried rider was located with a probe line an hour after the avalanche happened. He was unable to be revived with CPR and AED at the site. The avalanche appeared to be 2-4' deep, 500' wide, 600' vertical, and broke on weak snow near the bottom of the snowpack. AMu-HS-R3/4-D3-O

Our deepest condolences go out to the family, friends, and those involved.  

Full report available here: http://www.mtavalanche.com/accident/22/12/31

...we rode over the saddle between Sheep and Scotch Bonnet and saw an avalanche that appeared very recent, and likely triggered by a snowmobiler. It was on a west facing slope at 10,000', and was a hard slab 1-4 feet deep and 150' wide, ran about 200' vertical. AMu-HS-R3-D2-O. This was a clear sign that weak layers exist, especially where the snowpack is relatively shallower, and recent snow has been drifted into thick slabs that are unstable over this weak snow.

From observation: "Snow above collapsed into the trench from my sled, looked to have broken on a weak layer about 1.5’ down."

From observation: "Toured up to the east face of Mt. Blackmore today. We observed two small natural loose dry avalanches occurring right around noon on the new/old snow interface at about 9700' on the E aspect. The largest one ran about 200 feet down into the bowl. 

We observed a hollow snowpack on our ascent and dug a pit at 9600' just below the northeast ridge. We found several weak layers that were fracturing beneath two well-defined crusts. We got a CT2 @ 135cm, CT11 @ 130cm, CT13 @ 118cm, and CT15 @ 115cm; in our extended column test we got ECTP15 Q2 @ 130cm."

Snowmobile club members texted me that they triggered a 3' deep slab, that ran 100 yds., from connected terrain in Frog Pond Basin.  It sounded like a heavily wind loaded slope.     

Natural avalanche from the top of the popular snowmobile climbing spots on McDermott Hill in the Flint Range near Philipsburg.  There have been several close calls and a fatality in this same path.  It is named for the person who was killed in an avalanche there in the 70s.  It appeared to be a wind load on the ridge that initiated the slide.  In the background of a janky video, it appears there were other naturals as well.  The slide ran an estimated 800 ft, but no other information was obtained.

From Obs: "Observed recent small wind slab avalanches under the ridgeline as well as one larger slide that broke on weak snow near the ground, likely caused by cornice fall."

From BSSP: "The avalanche factory that is The Wave did indeed go into production today. A 2lb. shot in skier’s right Castro’s Shoulder initiated an impressive deep slab avalanche that took out Castro’s Shoulder through Wave South above Vuarnet Cliffs. The secondary start zones under these paths- Castro’s Beard (south half) and Mike’s Rodeo- also avalanched away.

The bed surface appears to be the top of the original big storm in October that forms the base of the snowpack on Lone Mountain. There is a melt/freeze crust at the top of that layer, with
small grained (mostly) facets on top of the crust, with the rest of the season’s snowpack sitting on that weak
interface.  

This [wide] propagation may be the result of the surface wind slab formed in the past few days finally tying the paths together enough to allow for such propagation.

The numbers are impressive- estimated crown length of 1,100 ft., crown depth of 3-4’, vertical run
of 1000 ft., and linear run of 2000 ft. We classified the slide as HS, AE (2lb.), R4/D3.5, O/G. Unfortunately,
conditions rendered good photos difficult. All the paths that avalanched have been shot repeatedly, almost
daily, all season long...."

This natural avalanche looks to have broken about 1 foot deep and stepped down to the ground on the steeps. It likely released during the storm.

On 12/28/2022 from the lower south boundary of Bridger Bowl, ski patrol saw an old avalanche crown and debris on steep rolling terrain below the large cliffs on Saddle Peak. Appeared to be 1-2 days old, 2 feet deep and 60 feet wide, N-R2-D2-O

From BBSP: "North of our boundary a natural avalanche was observed on the south end of the lower Bradley's Meadows ridge.  A point release originated in the south facing cliffs.  When it hit the steep knob above the gully it pulled the facets off of the rocks and willows, depositing an approx 4ft deep pile of debris.  There were old tracks on the slope and no one was caught."

A rider triggered shooting cracks on a slope northwest of Cooke City. 

From email: "There was upside-down trail breaking in the lower elevations today, and hazardous conditions around 8700' as the slab got thicker. The cold temps of last week definitely weakened/ faceted the snow in the thinner snowpack areas.

I intentionally triggered some cracking and a D1 soft slab remotely. The slab was about 6"-1.5' deep and about 50' wide.  It was a SE aspect around 8700. 

Above 9k', the snow structure was looking better, and I was getting ECTNs (snowpit attached), and no more collapsing nor cracking."

location:

Northern Madison Range
9,400 ft (below ridge top leeward and trees) 
130° SE aspect
110cm Depth of Snow
24° slope

CT 12
ECTN 11 @ 20cm down

Widespread collapsing.
Terrain choices:  very simple

We saw two large avalanches in the 2nd Yellow Mule that were probably 2-3 days old, and likely broke on the weak layer near the bottom of the snowpack. Hard slabs on heavily wind-loaded slopes. 

photos attached of some recent natural avalanches observed north of Cooke City today.

They all appear to be on N through E aspects, and primarily NE.  

Elevations between 9,000'- 10,000'.

While driving from Cooke through Yellowstone saw a couple recent natural slab avalanches. One on Amphitheater peak appeared to involve recent storm snow. And there were many relatively large wind slabs in Yellowstone (4-5 that I saw).

GNFAC forecasters watched a natural avalanche come down from Republic Mountain from the motel door in Cooke City at 8 am on 12/21/22. Couldn't see details of the slide other than the debris running over the cliffs and powder cloud in the trees below. Likely involved new and windlbown snow, but that is pure speculation. 

A local guide reported watching several other natural avalanches running off Republic Mountain as he drove into Cooke City around 7:30 am. 

On 12/21 we observed the remnants of a small natural avalanche (probably failed last night) on Scotch Bonnet immediately to the north of the Rasta Chutes. Approx 100 ft wide and ran 200 vertical ft. 

Today we toured up Beehive Basin to Prayer Flags and down into Bear Basin. We found moderate winds transporting snow at Prayer Flags. We also observed a recent small natural avalanche that broke just below the cornice at prayer flags (9200'). It was unclear if a cornice collapse triggered the avalanche. We did not go to the crown, but estimated it to be about 20-30 feet wide, 6-8 inches deep, and running less than 100 feet (Photo attached).

During our tour we saw lots of pillows of wind drifted snow and locations where slabs of wind drifted snow collapsed and cracked under our skis. 

In Bear Basin we dug a pit and found weak faceted snow on the ground. We did not have any significant test results, but the structure along with the wind and recent avalanche activity was enough to keep us off steep slopes for the day. 

The snow surface was powder in protected places, breakable wind crust in others, and either scoured or wind board at ridge lines.The skiing was best on low angle slopes protected from the wind. 

From obs "I skied on the east side of the Bridgers south of the ski area today. We dug a pit on an east aspect around 7300' and found 80 cm of snow with a similar structure to the more southerly parts of the advisory area. Well developed 2mm FC with a few DH cups sprinkled in made up the lower 40 cm or so of the snowpack (ECTP 21 on this layer) with the remainder consisting of 4F to F+ DFs. There was a razor thin "wind skin" I felt while skiing in more open areas below treeline but no major wind loading was present until at or near the ridgeline (pretty robust cornice development already for this time of year though). On our way back up just below the ridge around 7700' I felt a very large collapse that radiated out from my skis and shook some snow off of nearby branches."

We skied on the knob Saturday and Sunday. Dug a pit on the east facing slope just above the steeper roll over. ECTX. No result. Minimal wind loading next to the tree bands. We skied the slope 20+ times (between 4 skiers). 

We took the sled up track around the north side of the knob and below the avy debris from the slide triggered a last week. Only sign of avalanche activity (other then the obvious one) was a small wind slab release on a south facing slope near the top of the pass. Marked on the map below. Photo attached is of the previous slide but the wind slab release would be where the red X is if the photo continued. Looked to be 30ft across, ran for 15-20ft and about 6inches deep. 

From obs: "Natural wind slab, likely triggered by cornice fall in the last day or two, on a NE aspect at 8500’. Propagated ~150’ wide and ran probably 300’. Slab thickness seemed to be 18-24” at the thickest. No sign of stepping down deeper into facets in the snowpack, although adjacent to this slide there was evidence of an older slide (previous to recent storm cycle) that failed deeper in the snowpack."

Went on a tour today with a buddy and traveled through twin falls basin as well as the maid. We skied a NW slope off of Palace Butte and found touchy conditions below the ridge line, but great skiing in the trees. We also skied the bowl of Arden peak. We observed numerous recent wind slabs that released naturally in the past 24 hours on NE and E aspects with some crowns starting to get covered up throughout the day. Judging from afar, I would estimate these crowns to be 6 inches to 1.5 feet deep. 

From obs: "Thin and variable snowpack in the Specimen Creek drainage. The Max depth was less than 100cm, and the minimum was the depth bare ground. Active wind loading on exposed ridges, multiple whumphs when skinning over wind loaded, low angle slopes. Decent skiing, albeit thin, on low angle W aspects from 8200’ down."

Skier triggered avalanche on Saddle Peak. 12/16/22.

From obs: "I got to the top of the south summit around 11am with lots of active wind loading. I traversed the ridge line for a couple hundred feet, kicking away at small cornices to see if I could trigger anything. Got two small 6-8” deep soft slabs to propagate 10’ wide and a couple hundred vertical but nothing major. The ridge line is too rocky to traverse right now so I dropped onto the face, still staying near the ridge line. A hundred feet or so further across my traverse, it got deep. Cross loading from the north grew a drift that was thigh deep at least. Very cautiously I tried to regain some elevation to get above anything that might pop off. A few steps up the drift, I heard a whumph and it started to slide. I would estimate 2-4’ deep, 150’ wide. It immediately caught my skis and started taking me down. I pointed them down hill and started to pick up speed hoping I could cut out of it. It started getting very deep and turbulent so after 200-300’ I pulled my airbag, while still trying to stay on my feet. Thankfully, I was able to stay up and cut out of the slide roughly 500’ below the summit. It ran full length into the bottom of Argentina bowl and south gut with a massive powder cloud. Way too close of a call. I skied down the avalanche path then back to the resort with my airbag deployed in case of any other slides coming down. Made it back to the resort touched base with ski patrol to alert them of the slide, give them information on my condition and the possibility of other skiers out there (no possibility, I was first person up and didn’t see anyone ascending from the gate when I crossed to south summit) and headed home."

Small natural avalanche along the 2nd Yellowmule ridgeline. Observed 12/15. Looks like it likely broke during the snowfall 12/14. ~20 ft wide and ran ~50 vertical feet. Less than a foot deep. Wind drifted snow. 

From facebook on 12/15: "Saw a recent avalanche on a S/SW slope near Daisy pass. 2-3' crown and the avalanche arrested on the summer road. D2 in size. Also saw a large debris pile as you enter sheep creek on S/SW slope off of Miller ridge. Could not see crown, but debris was D2.5 in size."

Went on a tour today with some buddies with hopes of skiing the great one. Once up in the sac bowl, we opted to back away given the wind was howling. We skied the white worm, and saw numerous cracks shooting across the slope. I opted to ski a short and sweet N facing couloir which started out pretty firm into avalanche bowl. About halfway down, I had a wind slab release after one soft turn with the deepest portion of the slide being one foot. I was not carried as I immediately cut out of the fall line, the slide rolled for about 200 vert. My friends opted to ski the direct headwall exit and had numerous small wind slabs pull out. Some areas were stripped to rock of snow.

Cornice dropped in Slats and propagated slab at a weak layer of facets around 70cm height from ground. Dug a snow pit of 140cm and got etc results on the same layer ECTP26 stubborn but holds a large consequence.

Small slide from the cliff bands at about 9500’, on a NE facing slope on Blackmore - looked like it broke pretty shallow sometime after the snow yesterday.

On Dec 9, 2022 around 1:30pm we triggered a large, deep slab avalanche while riding across a lower angle slope below. This occurred on Fisher Mtn. near Cooke City on an east-northeast aspect at 10,000'. It broke 3-6+' deep and 300' wide. One rider was caught and carried, not buried, and luckily nobody was injured.

We saw an R1-D1 across the bowl of Sunlight Basin that looked recent after digging a pit near the weather station. While sledding around the area, we noticed faceting snow at the bottom of the snowpack in multiple locations.

Two small natural avalanches observed on likely wind loaded easterly aspects on slopes around Cedar Mountain at roughly 8,000’. 

There was a human-triggered avalanche near Chimney Rock on Henderson Mountain. The avalanche failed on weak snow near the ground. We believe a snowmobiler triggered the slope.

From GNFAC visit to crown 12/8: "We rode to Daisy Pass to look at the avalanche that was triggered by a snowmobiler two days ago (12/6/22). It was on the slope east of the pass that people often climb up and out, steeper than the normal route out. It broke 2-3 feet deep and 250-300’ wide, R2-D2. At the crown it broke on a weak layer about 100cm above the ground, but it broke closer to the ground in many places lower on the slope where the snowpack was shallower and weaker. I would guess one of those areas is where it was triggered from."

From IG: “Avalanche spotted on Henderson bench today, appears to be cornice triggered yesterday or the day before. 2-5 feet deep, 600’ wide, ran 800 vertical.”

Cut a wind slab from the top of the John at 2:30 in the afternoon.

3-6” crown. 50-75’ wide. Ran down to the low grade below

Observed active windloading on the eastern side of Lick Creek today.

12-18 inch slab broke easily when ski cut and a small but very reactive cornice was rapidly building.

Two skiers triggered an avalanche while ascending the Banana Couloir on Ross Peak on the morning of 12/5/22. The skiers were approximately 150 ft from the top of the couloir. The avalanche broke 20 ft above the upper skier. The slide broke in wind drifted snow 6 inches deep and approximately 30 ft wide, across most of the couloir. The lower skier was waiting in a "safe spot on the side" but was also caught by the slide. The slide ran ~600 vertical feet, pulling out a deeper pocket of snow (1.5-2 ft deep) midway down the path. Both skiers were fully submerged as they were carried, but ended up partially buried near the toe of the debris. One skier had snow packed into his mouth and underneath his eyelids. They returned to the trailhead under their own power. 

Small avalanche below Henderson Bench. SE aspect. Likley Snowmobile-trigger did not confirm. 70-90’wide, 1-3’ crown, ran 40’

We dug a pit on a W/WNW slope at around 9100 ft in the republic creek drainage. CT 18 and ECTN34 (ECTX then we hit it extra hard 4 more times) on the weak layer about 70 cm down. But overall snowpack was upright and it seemed to be settling down more than we thought. But then as we approached the ridge we triggered 5 separate large collapses ("Whumphs"), all on WSW/SW slopes (between 8700 and 9200 ft). Pole probes revealed a light crust about 12 inches down. 

Obs 12/3/22:

"Large collapses on primarily solar aspects (S/SE, ~9,500’)."

"Lots of whumphing but not much (if any) cracking...:"

"We toured to Ernie Miller today and saw a natural avalanche on a NE slope around 9600 ft. We heard and felt multiple collapses on our way in. We dug a pit on an east facing slope around 9300 ft where we found 105 cm of snow. We got a ECTN 2 result, failing on an interface about 15cm from the surface and ECTP5 failing 40 cm from the surface."

"Toured up to Bacon Rind today and skied meadows off of the ridge. Noted many collapses and whumpfs in the snowpack as we ascended east aspects to the ridge."

From IG 12/3: It was natural. Happened last night or this morning. It hadn't slid when we left yesterday. We were first tracks in today, and there were no tracks above or below this slide. Crown at the peak was around 6'. Average 2-3' crown. 10' debris piles at least.

Leaving Cooke on 12/3 we saw eight natural avalanches that likely broke on 12/2. Estimate more than 50% of slopes facing north, 8,000-9,000' had crowns 2-4' deep. The largest on Old Man Ray's below republic was R3-D2.5, 500' wide, 1,000' vertical (separately recorded). There were a couple, possibly larger, on Thunderer in the park, but low light made them difficult to confirm.

Leaving Cooke on 12/3 we saw many natural avalanches that likely broke on 12/2. Estimate more than 50% of slopes facing north, 8,000-9,000' had crowns 2-4' deep. The largest on Old Man Ray's below republic was R3-D2.5, 400+' wide, 1,000' vertical. There were a couple, possibly larger, on Thunderer in the park, but low light made them difficult to confirm.

From IG 12/3: Confirming more of what you saw, lots of large natural avalanches up high. Most notable was this massive slide on fox, looks to have broke 2-6’ deep and over 1000’ wide. Couldn’t quite see the toe from our tour but it looked to have run over 1000’ vertical. Never have seen one so large on Fox… 

Toured up to Bacon Rind today and skied meadows off of the ridge. Noted many collapses and whumpfs in the snowpack as we ascended east aspects to the ridge. Looking toward Ernie Miller ridge, we noted an old crown in the main bowl just below the summit. It was on an E-NE aspect, 200 or more feet wide and looked to be filled in with new snow but was still visible. Looking east from the top of the ridge, we noted another crown on a west aspect that looked to be about 100' wide and deep.

From obs on Mt Blackmore 12/2: " we were able to easily trigger shallow, short running windslabs by knocking down small cornices."

A number of large avalanches observed along Lionhead Ridge on 12/2. 

Near Cooke City (12/2/22) we rode to the cabins at Lulu Pass, then to Round Lake, then to Daisy Pass. Visibility was 50/50, so we didn't see all terrain clearly. We saw multiple large natural avalanches that broke last night or early this morning.

The largest were 3 on Scotch Bonnet (R2-D2, south-souwest aspect at 10,000'), 1 on Henderson in the big east facing slide path (R1-D2. east aspect 10,000'). These appeared to be 3-4 feet deep, and we suspect broke on a layer of weak snow that formed last week and is now buried 2-3 feet deep, and deeper on high wind-loaded slopes.

(We also saw 4-5 smaller wind slabs (R1-D1).)

Toured up to the NE shoulder on Mt. Blackmore yesterday. Winds were strong and variable, but mostly gusting from the S-SW. A lot of snow was moving around, skin tracks were filled in very quickly, and you could actively see small cornices starting to build on the lee side of the ridge. 

On the descent, I intentionally triggered a small wind pocket in one of the chutes in the cliffs near the trail at 8700 ft. I included a video. It was D1 and about 5 inches deep at the crown. I think just a good reminder that even in the trees, the tops of those chutes get wind loaded and can definitely slide. 

From BSSP Observations: "A wind slab triggered near the top of Cold Springs ran down and triggered a persistent slab around constriction level (see pics). This deeper failure occurred about 20cm off the ground at the Oct/Nov interface in a snowpack that was only about 1m deep." 

Skier triggered wind slab avalanche around 2pm, along the edge of north Bowl and Bronco near "The John". Crown 6-10" deep and 30 feet wide, hard slab of recent drifted snow. HS-ASc-D1.5. Strong wind blowing steady from the south-southwest and transporting snow, filling in tracks rapidly.

Immediately after this slide, I saw what I assume was skier triggered, slide of similar size a little further down the bowl with crown drifting in. Beacon check of debris produced no signal, barely deep enough to bury someone.

From obs: "Triggered a small(d1r1?) wind slab off the bridger chair in bounds at bridger. Little skiers right of bumble chute on the roll over skiers left of bronco. NE face. Rollover around 35 degrees mellowing throughout the run. The face had tracks from earlier today before i triggered the slide. I was able to self arrest and stop myself before being carried. The crown was around 20-25 ft wide and the slide ran roughly 100ft downhill before stopping. Both myself and my partner skied away unharmed."

Saw a group of skiers trigger a small wind slab avalanche on an eastern aspect at around 8,300' in the main fork of Hyalite in "Candy Land" just south of the climb Big League Chew at 2:00pm on Saturday (11/26). Crown looked to be around 2" to 1' and 90' wide. The slide ran maybe 100'. No skiers were caught. It was triggered as the first skier traversed out onto the intended ski line from the trees which they skinned up. The fracture extended from the tips of the first skiers skis and ran across the slope and underneath a small cliff band. The group skied out on a slightly lower angle slope adjacent to the slide. My group watched from below an adjacent ski run approximately 300 yards away as the slide happened. We had dug a pit on a similar aspect in the area approximately 30 minutes before the slide and found 85cm of snow with a weak layer at 42-45cm which failed CTs but we couldn't get propagation. (CT22, ECTN21). It looked like this was probably the layer that failed in this slide.

Obs from Beehive 11/25: "Lots of moving snow on south facing aspects. most of the chutes to the [lookers] right of the (4th of July couloir) had slid, it looked like it was mostly limited releases from sun warmed rocks."

GNFAC Forecaster at Bridger on 11/25 saw natural rollerballs and pinwheels on steep, rocky south facing terrain. (photo).

From BSSP (11/24): "The Whale on the NSS slid naturally at some point in the past 24 hours,
likely broke into deeper layers, and ran well past the Meeting Trees- estimated D3 slide. There is
weakness in the alpine snowpack on some northerly aspects in the alpine..."

From BSSP (12/4): "[A] team got a better look at the natural avalanche that occurred out there around
Thanksgiving. It was a solid D3.5 and ran full track from the level of the Little Couloir down to the
mature tree line."

From IG Message: "I read the avalanche report this morning and felt comfortable skiing. we made a plan to ski Bradley’s Meadows but ended up skiing Bridger Gully to the 3 Bears after discussion and feeling comfortable and confident in the snowpack. we did not experience any whoompfing or have any other concerns on the approach. 

The bottom of Bridger Gully to 3 Bears is where I triggered the avalanche. My partner dropped in first and skied safely out of the potential slide area. I followed up and on my first turn, triggered the slide. To me it looked like it was around 8” deep and was around 15’ wide at the crown.

My partner had eyes on me the entire time as the slide carried me about 40-45 yards. I was on top the entire time and was able to ski out at the end. I suffered no injuries. 

We skied out and talked to other skiers about our experience."

From Obs: "I wanted to share about a small avalanche I set off today. Snow was getting warm on my way up 4th of July couloir (pinwheels coming off lookers right wall started around 11:30) top half took a long time due to deep snow so I was suspicious of the pinch. Ski cut it during the descent (12:30p) and set off a wet slide (point release) that picked up quite a bit of steam as it came out the bottom. Big enough to injure/bury a skier."

Skiers at Bridger Bowl observed a small avalanche that was likely human-triggered on the Lower Nose. New snow and wind combined to created instabilities on slopes. The ski area is closed and represents a backcountry snowpack until the ski patrol begins avalanche mitigation in preparation for the opening. 

At 1:30pm on 11/23 I intentionally triggered a fresh drift of snow in a narrow avalanche path along the edge of the north bowl at Bridger. Northeast aspect at 7,600’ elevation. The crown was 6-8” deep consisting of snow that fell today, 20’ wide and ran 250’ vertical. SS-ASc-R2-D1.5-I. 

Wind was moderate, gusting strong out of the north and west and transporting snow. There were 3-4” on lower mountain and 7-8” new up high. Snowpack is 1-2’ deep. Prior to this storm, snow close to the surface had turned to small (1-1.5mm) facets during previous cold weather, capped by a thin crust (wind or sun) on many slopes. 

From IG message: "We saw a few decent sized point releases in the same zone on Sunday, 11/20, the day after the wind slab. All occurred on SW aspect within approx 15 min at 2:30. The air temp rose noteably shortly before and the sun was baking the SW aspect."

Triggered with 4lbs, after they were not affected by 2lbs shots yesterday. The crowns were in the 12” range and hard slabs. The weak layer is subtle-trapped lower density (but still 4F) above the crust, with tiny facets mixed with rounds. The slides were not running directly on the crust, but just above, leaving 2-3 cm’s behind on top of the crust.

My partner and I were skinning up a west-facing slope in Beehive Basin when we stopped out of the wind at a large rock outcrop.

Shortly after stopping to re-assess, a small, wind-deposited, pocket of snow popped off the rock face above us triggering a soft-slab slide which gained momentum and stepped down through a rocky choke, fanning out in the open face below the rocks, before coming to a stop directly at our skis. 

We witnessed no additional natural avalanches that day or found any significant instabilities in the snowpack on adjacent slopes. We can only attribute our near-miss to luck, if the avalanche had occured five minutes before we stopped (while skinning across the slope), or five minutes after (while continuing upslope to our desired objective), our day might have ended quite differently. 

Toured into divide basin on Friday. Looking at the north face of hyalite peak we saw a slide that went to the ground, and was about 150 feet wide. It possible this slide propagated further, but severe wind loading was actively occurring and it was hard to tell if the crown had been filled back in. We dug a pit at 9300 feet on a SÉ aspect and found a 80-100 cm HS and right side up snow pack with minor faceting below a crust 30 cm from the bottom. 

From obs: "triggered a small wind slab in sluice box today. this was not a surprise as all of the wind loaded areas had shown cracking and instability on the way up. though these other areas exhibited the same instability, this little pocket in sluice was the only spot steep enough to run."

submitted to us via IG: "triggered this large wind slab below Bridger Lift this morning [11/18]. It propagated quite a ways."

Small wind slab avalanches (both natural and skier triggered) along the Bridger ridge and in Beehive Basin.

See obs:

Bridger Obs

Beehive Obs

From email: "We noted one recent slab avalanche today on a NE aspect of Mt. Henderson, around 10,000.  We were skiing nearby on Nov. 11-12 and did not notice this slide, but that may have simply missed it (that slope becomes shaded by about noon this time of year and there was lots of wind affected snow in that area.)"

A number of Avalanche Crowns on an east aspect at 9500 ft.

From email: "Skied around Mt. Henderson the last 2 days-... we experienced at least 6 large collapses while touring the last 2 days, often after 10+ people up the same skin track."

From obs: "Skied Hyalite Peak today and found a wind slab ~10cm deep. Ski cut a small cornice below the main face and broke a small slide that carried ~20’ with little energy with a ~25’ wide crown"

"... a small wind slab avalanche (R1 D1)  from yesterday at approximately 7800 feet on the northern end of bradleys meadow. The slide was initiated by the second skier and although the rest of the slope was <30 degrees the starting zone was a NE facing steep cross loaded wind pillow just below the ridge. 

As my friend was skiing down he saw a crack propagate up and to his left and was able to stop on the side of the path as the snow ran past him. The  crown was approximately 30-40 feet and ran about 100 feet. 

Here are the coordinates of  a way point I dropped just above the top of the slide : 

45° 50.0218′ N, 110° 55.7420′ W

 we circled back and took a photo of the top as well...  "

From IG: "Remotely skier trigger wind slab up on white worm near sac bowl".

A skier remotely triggered an avalanche on Mt Blackmore (11/9/22).

From email: "I ski cut the top of the face and remote triggered a hard slab from 50’ above the crown. It broke full width of the couloir feature, 150’ wide and 10-18” deep. Broke on new snow/old snow interface which was another hard wind slab. The avalanche ran the length of the East face and stopped just below the last set of cliffs."

From obs: "Saw some cracking and propagation of a 6-8" storm slab on steeper terrain near the Bridger Lift. Gentle upslope winds seem to have compacted a slab near some terrain features, and I got a small propagation at the edge of the Sluice Box gully where the slope angle tipped up near 40."

Small slab avalanche triggered by skier in a small chute near The John and Bronco runs in Bridger Bowl. Propagation from skier’s ski, slab slid down through the chute. Crown maybe 10 feet wide. Slab looked about 6 or 7 inches thick. Looked like a layer of new snow from today and yesterday’s storm sliding on top of an old crust layer. Nobody harmed, just spooked. Watch out!

While traveling up the Fairy Lake road, we observed the aftermath of an avalanche in October Bowl. The avalanche was D2-D3, start zone was at approximately 9000 ft, north east aspect, crown depth and width is unknown.

BB skiing in the past few days. Pretty impressive single-storm coverage. Skied from the top of the nose down to the base on Wednesday. Spotted a few micro wind slabs that had peeled during the storm but nothing large.

Big Sky Ski Patrol saw evidence of a natural avalanche in the closed ski area. 

From email: "saw evidence of a large avalanche that ran in 3 Forks area of The Headwaters... NE aspect in the probable start zone (could not see a crown) that likely saw significant wind loading Monday.  It ran full track and broke some branches and small trees in the runout. 

That was the only activity I saw (3 Forks is an avalanche factory with large storms).  Definite wind effect across the alpine."

A group skiing at Bridger Bowl observed at least one point release south of Saddle Peak above a cliff band. It appeared to be due to warming surface snow from the sun. 

A group saw debris from an avalanche coming out of Hidden Gulley and down into the Apron at Bridger Bowl. Bridger Bowl is closed and there is no avalanche mitigation or ski patrol activity. 

Skiers driving to Beehive Basin observed an avalanche from the road in the area. Minimal details