Snow Observations List

With another day of high pressure and clear skies, Alex and I rode into Lionhead and parked the snowmobiles at the top of Ski Hill. The coverage in and out was decent for this time of year, but thin cover and sharks abound. We dug a snowpit at the top of Ski Hill (8150')  and then toured up to the south end of Lionhead Ridge and dug there (8650').

Our snowpits told very similar stories of a weak, layered snowpack from top to bottom: glittering surface hoar on top and different variations of facets to the base. In both snowpits we got ECTN's on interfaces between faceting snow. In our upper pit, we noted a more cohesive slab on top, but it was just not enough to get propagation in that spot. 

As we skinned up the ridge, we also noted very isolated collapses, one to two feet from the tips of our skis. But overall, there were no signs of instability, just weak snow, growing weaker by the day. 

Until the next round of snowfall, our main hazards continue to be the rocks, trees, and stumps just beneath the surface.  

We skied around Scotch Bonnet and Sheep Mtn., north of Cooke City today.

No collapsing nor cracking, nor any avalanche activity observed.

Snow profile attached from a SE aspect at 10,000' on Scotch Bonnet.  HS65, ECTP22 @25.

Surface hoar (4-8mm), observed on most slopes, except on steep solar slopes and especially windy locations.

Today, Ian and I rode Buck Ridge. The trail in and out was in decent shape with a few wind-stripped bare spots but mostly continuous coverage. We got eyes on First, Second and Third Yellow Mules as well as into McAtee Basin. Small, glittering surface hoar covered most aspects. At the head of Second Yellow Mule, we dug a pit on a NE aspect at 9400 ft and found a snowpack with weak layers throughout: surface hoar and near-surface faceting at the top and faceted snow near the ground. We got an ECTPX as we just didn't have the load on top of these weak layers to cause slab formation or propagation. 

In general, we did not see any notable dry-snow avalanche activity or signs of instability. Despite sunny skies, the snow surfaces we rode on stayed dry. One small loose-wet avalanche on a S facing aspect on Eglise Rock was observed that likely broke in the last day or two. We also noted a few reported wind slabs that broke last week. 

Our main hazards today were the early-season coverage and buried obstacles. 

We rode into the Taylor Fork to the weather station and then over to the wilderness boundary. The trail in and out was in decent shape. The riding in the Taylor Fork was very thin with plenty of barely hidden obstacles. We moved slowly through the terrain and managed to avoid the landmines. 

It was 12 degrees when we left the car, temps were warmer up as we climbed but, even under sunny skies, the snow surface never got wet. Dry snow conditions were mostly stable, with no wet snow instability. I would worry about hitting a buried log or rock more than triggering an avalanche. However, we did get a couple of propagating tests in a 60 cm deep snowpit at the edge of Sunlight Basin (ECTP18 @ 22 cm) and at the Wilderness Boundary in a 49 cm deep pit (ECTP14 @14 cm). 

The snowpack is getting worked by the period of high pressure... surface hoar and near surface facets up top and faceting at the base. We will continue to monitor the state of the snowpack as we move toward the next snowfall assessing the structure that will eventually get loaded. 

This was a nice walk to stretch the legs in the Taylor Fork. My observations largely aligned with what GNFAC fxers observed in the same drainage on the same day.

Deep temperature inversion was present, it was 3 F when I left the car at 10 in the morning, and I eventually climbed out of the cold pool of air around 8,200'. I stopped and dug a few roadside handpits on the drive in from 191, it was impressive how much additional faceting was occurring below the level of the inversion. Here, the snowpack consisted mostly of 20-30cm of facets (DH near ground), with a decomposing 4F ambient temp crust in the mid-pack. I had no stability concerns down low today, but this very weak lower-elevation snow will create problems with additional loading. With enough load I would expect to see frequent, long-running collapses as well as the potential for remotely triggering slides from long distances in valley bottom locations. Many low elevation slopes facing SSE-S-SW-WSW had lost much of their snow cover, but solar margins and anything tilted a bit away from the sun were holding snow.

Above the level of the inversion and continuing up into the alpine the snowpack looked a bit better, but not great. Faceting was less pronounced and I was unable to get ECTs to propagate in a pit dug in a relatively flat meadow at ~8,600' (which felt like a decent proxy for shaded slopes based on structure). However, shortly after leaving this pit I initiated a large collapse that traveled across an entire large meadow; the collapse was audible for over a second as it propagated. This collapse and the weak layer of concern in my pit is the widespread basal weak layer, buried beginning in mid-November. This was the only direct instability feedback from the snowpack I experienced this day.

In the alpine, snow surfaces were weathered and highly variable, presenting as a mish-mash of facets, crusts, thin wind skins, and stiffer, denser hard slabs from recent snowfall. None of these surfaces looked terrible, but I'd expect a quick load of snow+wind to find plenty of locations with collapsible weak layers capable of producing avalanches. I looked around for a place to dig and look at basal weakness but was unable to find anything of value due to this high degree of variability. There was a thin but widespread rime/humidity crust in the upper few cms of the snowpack that was present as high as I observed (11,000' +). I observed some cracking that had occurred previously in steep, heavily wind-loaded north-facing terrain. It was not perfectly clear if this cracking involved the weak layer near the ground or just the thinner, wind-drifted hard slab near the surface, but it seemed like it was more of a surficial problem. 

Lots of surface hoar. Those crystals are often destroyed before being buried, but surface hoar is a good sign of weather conditions that are good for near surface faceting.

The upper few inches of snow is a mix of broken snowflakes that are starting to facet a little bit. Not too terrible yet.

Deeper layers of old November snow closer to the ground are faceted and breaking in stability tests. To get an avalanche breaking on those facets, I think you need an old wind slab on top. Even then, I think the sensitivity has dropped a lot. 

We did see one recent wet loose avalanche that started near some exposed rocks in a place that typically gets wet. I did NOT see any wet loose slides in East and Southeast-facing gullies on Barronette peak. However, I'd be nervous ice climbing in these gullies when the sun is hitting them.

The snow Ranger Crew got out and about on Buck Ridge today.  Trail in was in OK shape but is likely to melt back and get worn down over the next few days from sun and sled traffic.  Riding started to get quite good above about MM7; snow was generally supportable and ranged from 50-85cm deep for the most part.  Open areas had some wind effect but there were few hard drifts/slabs.  Anywhere that was sheltered from the wind had a layer of surface hoar forming, not surprisingly.  The head of Beaver Creek was scoured nearly to dirt and the cornice is quite large there already.  We noted one small wind slab avalanche just below it.  We found a similar avalanche in Second Yellowmule that again appeared to be from wind loading.  Both appeared to be several days old.  We dug a quick pit on a north facing slope in Second Yellowmule and had an ECTN in 85cm of snow.  Only the bottom 5cm or so of that pit were sugary and faceted.  

Snowpit from yesterday attached.   West aspect 9700'.  HS70, ECTP15 @ 23.

Some collapsing in the valley bottom, and also near the ridgeline- on both easterly and westerly aspects.  

Minimal wind effect.  Surface hoar to 10,000'.

From email: "Ernest and I dug a pit while setting up the yurt today, just off of the roundabout below the yurt. At 9410ft, NNW aspect, 10 degree slope, we found HS 75cm. The general structure seems right side up. There are facets at the bottom 20cm or so, but they are wet, and seem to be rounding. An ECT gave us ECTN20 at 40cm down. Here's a quick hand hardness profile. The bottom 20cm is slightly less hard than what's above it." Photo: N. Mattes 

We toured through Bridger Bowl to the top of Slushman's Lift. The deeper areas are around 2 feet deep. We uncovered many rocks during our descent. 

Wet Snow: We headed home by 1:00 PM, but that was enough time to see snow on southeastern and south-facing terrain warm up. Yesterday, there was an R2-D2 wet snow avalanche out of the run Close Call (see photo). This is a rocky, south-facing run. We saw limited pinwheels of warming snow coming out of rocky areas, and it seemed like planar snow surfaces would start to slide wet. Hopefully, things will cool down soon.  

Dry Snow: We did not see any signs of dry snow instability. Two pits were "right-side-up," meaning softer snow at the surface and firmer snow below with ECTX results. This is a good sign for stability. If folks push hard into steep avalanche terrain, someone will probably find an isolated pocket of instability, but we are looking good for now. The primary concern for now is how much the surface snow will weaken and facet before the next storm. Despite air temperatures near 40 degrees F, the snow surface was 21 degrees F. These large temperature gradients will drive rapid faceting.  

Headed north of Bridger Bowl today to get some early season turns. Skied hourglass couloir off the ridge where we found a shockingly shallow snowpack that featured a thin wind crust ranging from a zipper crust to a thicker 2 inch wind slab on top of the snow below. The slab was not significant or connected enough to propagate/show shooting cracks. Later in our tour, in areas where the snowpack was deeper and more protected, I was happy to find 50 to 80 cms of snow that was mostly right side up with soft snow on top on shady aspects. The surface snow was beginning to decompose but with the warm temperatures it is moving slow. I could still make a small snow ball with the surface snow. Within the snow pack there is very little evidence of faceting. On our way out, solar aspects were beginning to shed and there were a number of wet loose avalanches. It will be interesting to see how the snowpack evolves over the next few days. 

Skied over to Schlasmans yesterday. Early morning sun exposure on southerlies plus Saturdays wind led to a crust and or sastruggi setting up by mid afternoon. Northerlies were spared from the wind and still holding cold snow. A decent sized loose/ wet D1.5 came down between laps (probably 1300) in what i believe is called gangstas. South facing, steep, thin and rocky.  Not a place youd expect people to be skiing since there is poor coverage but a good reminder to watch out for overhead hazard since it ran out into Schlashmans gully. 

Flat light yielded a mediocre picture at best

We traveled up Beehive Basin and over the ridge at the prayer flags. The first noticeable thing was the deterioration of the surface snow. It was the hissing, recycled powder sound of faceting in the upper snowpack. Quick hand pits revealed 4F facets through much of the SW-facing terrain as we ascended the ridge. We dug to the north of the prayer flags. The 68 cm snowpack remained very supportable on skis, less so on foot. The basal facets and the near-surface facets are increasing. ECTP30 at 12 cm from the ground. 

The snow surface remains Fist hard in untracked areas. There is some snow available for transport but without a significant wind event, things will probably stay put. 

Stability is generally good and will continue to improve without additional loading. However the same cannot be said for the snowpack structure which, I fear, will continue to weaken. Not a good situation when snowfall returns. 

My partner and I dug a pit on the SW side of Divide Peak at 9200' and conducted an ECT test with a score of ETCN. Our snow pit was about 120cm deep, and the identifiable weak layer in the shovel shear test was an ice crust layer at about 30cm from the base. We did not find any of the faceting issues that have been reported across the advisory range.

Thanks for all that you do!

We toured toward Hyalite Peak and didn't go to the ridge because the wind was blowing so hard. We didn't observe any natural avalanches and only got localized cracking. The snow was still soft in the trees. 

Multiple pits yielded propagation in ECT test. Values varied between ECTP-9 and ECTP-22. Failures occurred on an ice crust ~20cm off the ground. 

Pits were ~8,400’ to 8,500’ in elevation on across the basin on eastern and western aspects of Beehive basin proper. All pits (3) exhibited failure. We also noted occasional collapsing in the flats. 

Intentionally triggered on a ski cut. Broke about 1 foot deep and 10 feet wide, ran on a hard compact surface below the soft wind slab. 

Went up the apron today and out to the ski area boundary. The skiing is still excellent, and there were tracks everywhere!

Dug a quick pit at 8000', NE aspect, ~30deg slope

Total Height of snow: 80cm

The snowpack is generally in quite good shape for this time of year. Right side up and wet snow at the ground! No primary layer of concern where I dug and the new snow seems to be bonding well. Because of this I did not perform any stability tests. 

Calm winds, overcast skies and balmy temps are most likely helping heal any wind slabs at upper elevations. 

One more note: It looked like a D2 propagated in Argentina Bowl. Observed on the drive in

Big Sky Ski Patrol triggered a deep slide in the Big Couloir during avalanche mitigation work on 11/28/24: "Summit north peeled the cornice way back to the ridge and took out the upper hanging snowfield before crashing into the Couloir, leaving a 5-6’ tall crown in the chute above the dogleg."

Dave and I toured into Blackmore basin today and skinned up the SE shoulder to the ridge. As we entered the basin, we immediately noticed several natural loose snow avalanches (R1 D1) in steep rocky sections of the direct E face. These looked to have occurred in the last 12 hours. Though they would not have buried someone, they would have strained a skier or rider through some nasty trees and cliffs.

Gaining the ridge, we could see there had been previous windloading on both sides. Cornice formation showed winds from the N/NW but, dropping onto the N shoulder showed evidence of windloading from the E/SE also. We dug two snowpits: one on the N shoulder and one on the E face. Varying snow depths ranged from 50-70cm and up to 90 cm in wind-loaded spots.

Our snowpits showed us two things: our snowpack is showing signs of early season faceting and our areas of most concern are wind-loaded slopes where there is a slab on top of that weak snow. In our snowpit on the E face, we got propagation at ECTP 16 at the interface between wind-blown snow and faceted grains. With this upcoming bout of high pressure, we will be continuing to dig down and see how the snowpack is changing under our feet.