Trip Planning for Northern Gallatin

Large avalanche on Mt. Bole seen by skiers on 3/17/23.

We skied the ridge north of Blackmore (Tomahawk Ridge?) traveling between 6800' -9200' on SE-NE aspects.

On the ridge above, ~9400' on a NE aspect there was a natural avalanche, maybe cornice failure, probably same timeframe as the Divide slides. ran ~600'.

HS-N-D2-R2-O

Photo: R. Griffiths

I went for a walk up to divide basin today and noticed two slides that occurred on high, steep, north facing slopes last night (Tuesday night) when the wind picked up 

While investigating an avalanche that failed on a weak layer of facets buried in January, we notice a new layer that we will be looking for and testing as we move forward. Photo: GNFAC

Investigating a recent avalanche on Hyalite Peak. Photo: GNFAC

On Buck Ridge today (3/5/23) we found fresh, unstable drifts. This fresh slab was 4-6" deep. Cracking like this is a sign that wind slabs will avalanche on steeper slopes. Photo: GNFAC

Skier triggered avalanche on Elephant Mtn. 3/4/23. SS-ASu-R2-D1.5-I

Vertical Fall: ~700' Distance Traveled: ~1000' Aspect: 15 N Elevation of start zone: 9645'

Skier triggered avalanche on Elephant Mtn. 3/4/23. SS-ASu-R2-D1.5-I

Vertical Fall: ~700' Distance Traveled: ~1000' Aspect: 15 N Elevation of start zone: 9645'

Skier triggered avalanche on Elephant Mtn. 3/4/23. SS-ASu-R2-D1.5-I

Vertical Fall: ~700' Distance Traveled: ~1000' Aspect: 15 N Elevation of start zone: 9645'

Skier triggered deep slab avalanche on NE face of Hyalite Peak 3/4/23.

Skier triggered deep slab avalanche on NE face of Hyalite Peak 3/4/23.

Skier triggered deep slab avalanche on NE face of Hyalite Peak 3/4/23.

"Chunk of cornice fell off the top of Arden Peak. Notably the same aspect/elevation as the 2/27 observed natural slide on E face of Mt Bole but the cornice fall did not step down beyond the surface snow." Photo: M. Zia

From IG. “I spotted a large crown this morning on the E face of Bole. The crown appeared to be pretty deep, at least a few feet, and propagated quite wide. It also looked like there was a debris path coming down the apron of the E face of Hyalite peak, but I was too far away to know for sure.” N. Sramek

From IG: Skiers near Mt. Blackmore on 2/24 saw a large avalanche on the east side of Mt. Blackmore that appeared to have happened in the last 24 hours.

From email 2/24/23: "Came across this very large cornice that appeared to have broken naturally sometime in the past 24 hours. Saw a few others that had broken recently throughout our tour, but none as large as this." E. Heiman

Low winds/no snow transport when I was up there and the east face had little to no wind effect, probably 16-18in new snow. Saw this slide with about a 8-12in crown and 100ft wide on the north face, didn’t see any other activity aside from some small point releases on really steep east aspects.

From another party: Saw a sizable avalanche on the north east face of Blackmore, likely broke mid storm and was partly filled in already - estimated 20" deep, 100' wide. Had shooting cracks and collapsing while ascending northeast ridge. Hand pits showed planar results on an 8" harder slab beneath all the blower on top. 

We observed a few small crowns on steeper road cuts in Sourdough today, NW and W aspects. 4-8" at crown, 20-40' wide, ~10' vertical. They looked like storm slabs that had run overnight, maybe on a density change in the storm snow. Debris piles were small and covered with 2-3" of new snow. Low consequence, but maybe enough to surprise a kid or a dog. Photos were taken shortly above the 2 mile marker.

Was about 80% of the way up to the top of the middle meadow on history rock this morning when we remotely triggered a small avalanche from the skin track.  Slide was just new snow that had fallen within prior 24hrs.  Crown of about 8 inches, 20ish feet wide by 20 feet long.  Face that slid was east facing.  We took this as a sign to reconsider skiing something even as low key as history rock and decided to ski the skin track back.

[Dropped the pin for this observation exactly where I believe the observation to have occurred.  Took an OnX waypoint while out there to help too.]

Went for a ski up the Flanders drainage in Hyalite today. The day was punctuated by light winds and heavy snowfall.

On the skin in, we noted numerous D1 storm slab avalanches about 15cm down in the new snow on many aspects and elevations. Approaching a ridgeline, we experienced a shooting crack that propagated a very small slide in slightly wind affected snow. We dug an ECT on a SE facing aspect at 9000ft. We were unable to get propagation. Snow totals appeared to be higher than forecasted, with 60cm of new snow as of about 12:30. By the time we ripped skins, the area had received an additional 10cm of snow, putting totals around 60-70cm of low density snow on top of a stout melt freeze crust on the aspect we were skiing.
 

we did not observe any cracking collapsing or wumphing in buried weak layers, nor signs of avalanches on those layers. The new snow had very low SWE.

I sunk to the ground on Mt Ellis when I stepped out of my skis. A poor, unsupportable structure is not everywhere, but it certainly was on the ridge. Photo: GNFAC

"Found widespread surface hoar up storm castle creek on all sheltered slopes above 7500’." Photo: JR Mooney 

2/11/23: "..we noticed a few old crowns that released before the most recent snow, hard to say if they were natural or not. We also observed a most likely remote triggered small wind slab (not our tracks next to it). Solar aspects were hot. Top of snowpack was relatively stable in our 4 foot pit, some collapse but no propagation (E aspect, 8400 feet). " Photo: Tommy S.

Karl Birkeland got an ECTP9 under a wind slab on the Throne. We could feel the hard slab and softer, weaker snow under it with our ski pole. Photo: GNFAC

We founds areas that were scoured to the dirt and adjacent areas loaded from the wind. The evidence of strong wind was everywhere. Photo: GNFAC

At the ridgetop of the Throne we found deep wind slabs that had cracked naturally; a sign of instability. Photo: GNFAC

From obs. 2/11/23: "...Also of note, as we traversed a corniced ridge later in the day, two of our group members simultaneously came too close to the edge of a cornice and it broke away, but did not fall down the slope. Fortunately, everyone was alright, but it was a close call..." Photo: E. Heiman

From obs. 2/11/23: "...Also of note, as we traversed a corniced ridge later in the day, two of our group members simultaneously came too close to the edge of a cornice and it broke away, but did not fall down the slope. Fortunately, everyone was alright, but it was a close call..." Photo: E. Heiman

Me and a buddy were out skiing/camping in the Hyalite Lake area. Late Saturday afternoon we started skinning up towards Hyalite Peak. The path up to the ridge was super hardpacked and windswept. We got up and there was quite a bit of snow loaded above the north slope. I dropped over the side and took about two turns before the entire face above me released from the very top and traveled down the entire north side down to the bowl below. I was able to get to the rocks on the side and my partner was able to pick his way down. The crown looked a few feet deep from what I could see and stretched across the entire top of the line.

Me and a buddy were out skiing/camping in the Hyalite Lake area. Late Saturday afternoon we started skinning up towards Hyalite Peak. The path up to the ridge was super hardpacked and windswept. We got up and there was quite a bit of snow loaded above the north slope. I dropped over the side and took about two turns before the entire face above me released from the very top and traveled down the entire north side down to the bowl below. I was able to get to the rocks on the side and my partner was able to pick his way down. The crown looked a few feet deep from what I could see and stretched across the entire top of the line.

Me and a buddy were out skiing/camping in the Hyalite Lake area. Late Saturday afternoon we started skinning up towards Hyalite Peak. The path up to the ridge was super hardpacked and windswept. We got up and there was quite a bit of snow loaded above the north slope. I dropped over the side and took about two turns before the entire face above me released from the very top and traveled down the entire north side down to the bowl below. I was able to get to the rocks on the side and my partner was able to pick his way down. The crown looked a few feet deep from what I could see and stretched across the entire top of the line.

A snowboarder noticed several small slides on the east-facing walls of the Main Fork of Hyalite Creek and a small slab avalanche in the back of the Divide Peak basin. This slide is in an area locally known as Candy land/ ice farm

A snowboarder noticed several small slides on the east-facing walls of the Main Fork of Hyalite Creek and a small slab avalanche in the back of the Divide Peak basin. This slide is in a area locally known as Candy land/ ice farm

From Obs: "Went skiing up in Flanders area and saw several avalanches with crowns ranging from 1-3ft deep and running a several hundred yards wide. Also experienced 2 whumphs and some cracks on a wind-loaded aspect near the ridge" Photo: B. Farrell

From Obs: "Went skiing up in Flanders area and saw several avalanches with crowns ranging from 1-3ft deep and running a several hundred yards wide. Also experienced 2 whumphs and some cracks on a wind-loaded aspect near the ridge" Photo: B. Farrell

From Obs: "Went skiing up in Flanders area and saw several avalanches with crowns ranging from 1-3ft deep and running a several hundred yards wide. Also experienced 2 whumpfs and some cracks on a wind-loaded aspect near the ridge" Photo: B. Farrell

From text: "went up to Champagne Sherbet to ice climb but then there was a big fracture on the approach! Got to a safe spot and dug to see - a strange drifted wind slab over the old belay area has created a scary snow cave trap! We bailed out of there..."

From IG message: "Another one today. Back of buck creek. Triggered 100 yards above where I crossed below it in the safe zone, after I went by. No burials."

From obs 1/28/23: "While snowmobiling up Little Bear we witnessed this natural avalanche. There was 2-3' of new snow." Photo: J. Otis

From obs 1/28/23: "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." Photo. S. Regnerus