Snow Observations List

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. 

We rode into Cabin Creek very delicately, and it was great to be riding in late November. Hitting rocks is the greatest threat. 

Overall conditions are thin but great to see so much snow.

9000 ft, N facing - 87 cm (~35 inches)

9100 ft, SE facing - 49 cm (~20 inches)

8100 ft, E facing - 35 cm (~13 inches)

Some faceting is occurring in the snowpack (aka - weakening), but the current state of the snowpack isn't the main issue. It's hard to appreciate how cold things are in the mountains and how cold the snow will get under clear skies. Clear nights in December will significantly weaken the snowpack, and it will look A LOT different the next time we come back. 

What we need? - Snow. We don't need a lot but a few inches every few days along with cloudy skies will help things a TON.

Where can you trigger an avalanche right now?  - I think you need to find a slope with recent wind drifts where you can either get a wind slab or persistent slab avalanche. 

Lastly - the radiation recrystallization process is happening as well. On an East-facing slope at 8100 ft at around noon, the surface of the snow was dry but snow just under the surface was damp. 

It was snowing heavily around noon when we left the Beehive parking lot but didn't last long. Light snowfall throughout our tour, 2cm of new snow on the skin track. Light wind at the ridgeline. No obvious signs of instability. We skied partway into Bear Basin, dug at the top of that steep rollover halfway down. HS 65, 8600', NE80. Got ECTP13 on a layer of facets about 25cm up from the ground above a decomposing ice crust.

Big Sky Ski Patrol triggered this avalanche during mitigation work in The Wave on 11/26/24... "2-3' deep on an ice crust just above the ground with a 2# shot in the Upper rodeo. Volume was limited as most of the snow was loaded just underneath the cornice, but still produced a sizeable size 2... Other paths in the Lenin region ran meaty wind slabs, full track with no significant step downs." Photo: BSSP

Snowpit from near Lulu Pass attached.  Localized collapsing on E, NE aspects between 9300- 9900', and no avalanche activity to report.

80 cm of snowpack on the lower ramp. Stable test results. Small layer of facets sitting on the surface and a small layer of facets under the most recent storm snow buried about 13 cm deep.

Driving up Bridger Canyon this morning, we noted several natural avalanches in wind loaded terrain on Saddle Peak, the Football Field, and in Mundy’s Bowl. All The avalanches seems to be a similar wind slab problem. They broke just below the cornice line. From a distance and considering yesterday’s new snow, I would guess a foot deep or so (R2, D2, I)

From email: "Northerly facing terrain harbors October snow, which has faceted. It is holding up plenty of dense snow and wind slab from the quite snowy and windy November. It was unable to hold the additional weight of a human trigger, and two pockets failed at the ground, which produced avalanches. Crown height maxed at 2’. Notably, where it did not avalanche, the failure propagated hundreds of feet down the ridge. It is a good data point- northerly aspects near tree line have potential instability."

Performed Stability test on Henderson Mountain today. Elevation 9600', SW facing slope. HS 85cm, New Snow 20cm. Of Note, 1mm Rounding/Moist Facets at ground with 1CM Melt Freeze Crust 60cm from surface. 1mm Facets on either side of MFcr. ECTN 6 at new/old snow interface and ECTN25 on MFcr 60cm down. Generally pretty good looking snowpack for November 24. No collapsing or cracking of the snowpack and no recent avalanche activity observed.

Took advantage of yesterday's fresh snow and headed to Beehive Basin for a short tour searching for soft snow. I did not make any formal observations on the day, but dug a handful of quick hand pits and probed for layers on a number of aspects. Our travel varied on all aspects except for true north facing slopes and we stayed between 8000' and 9000'. There seemed to be about 4-8 inches of fresh snow that fell on a variety of surfaces ranging from melt freeze crusts on solar aspects to snow that stayed dry through the last warm-up on shadier slopes. There was very little evidence of wind on the new snow and fresh cornice formation was minimal.

Overall snow depths ranged from about 2' to 3' and coverage was quite good for this time of year. Shadier slopes yielded an encouraging snowpack that felt mostly right side up with relatively strong grains. The new snow was not forming any real slab. On solar aspects the snowpack was much more variable/upside down and the snow underneath the melt freeze crust felt weak. On one particular hand pit, while cutting a block, the new snow and underlying crust failed in the old snow as one cohesive piece. Overall, great day out, with awesome snow, and I am excited about what I'm seeing for the most part. 

Dug near the bottom of the Apron in a zone between the Apron and NW Passage.

NE aspect, 7500 ft, 29 deg slope angle 

Total depth = 95 cm

Snowpack generally good, and the lower snow is surprisingly dense and strong for an early season snowpack. Yay!! There are a couple weak layers in the upper 20 cm, one was the interface with last night's new snow and the other was some graupel, but both only produced ECTNs. 

ECT results

- two ECTNs in the upper 20 or 25 cm with less than 10 taps, one ECT in the lower snowpack with about 22 or 23 taps. 
 

Nice snow and the parking lot was filling up by the time I was back at my car. 
 

I went searching for facets on the Ramp today and came up short on my results. The snowpack is still thin and the few measurements I took showed about a 50-60cm HS in most places. On the ridge itself at 8500', winds were blowing strong from the W, and at mid-mountain, gusts were strong enough to blow your hat off, but the Ramp itself remained relatively non wind-effected. In the few handpits I dug, I did not observe any sort of slab formation, nor faceted snow, but noted about 10-20cm of dense powder on top of moist snow to the ground, especially in thinner areas. I dug a quick pit just off from the ridge and noted an HS of 55cm with an 3cm decomposing crust about 29cm up from the ground. Snowpack ranged from fist hardness down to 1 finger at the base. And though the grains at the ground had some edges and corners, I did not note truly faceted snow at the base. Another thing: around 14:45 a strong burst of graupel fell for about 10 minutes that then changed to snowflakes. The pulse of that storm was dying off off by the time I skied off the Ramp around 15:30. 

My main concern today were all the limestone sharks still very present out there, but in general N/NE facing aspects up high held good snow even after these warm temperatures! 

Wind was ripping on the ridge and creating hard wind slabs 3-6” in depth. Without much new snow to transport they weren’t very large or widespread, but we got cracking and propagation on a steeper terrain feature (Hidden) near the ridge that led to us skiing a different line. The slab development was also found in isolated areas further down from the ridge in cross loaded gullies, but slabs were isolated to breaking at the skis. 

Warm, stormy day. Winds moving a lot of snow around Sawtelle

Sawtelle Pk, Island Park

• 6500' - HS 30cm
• 7000' - HS 35cm
• 7500' - HS 40 cm
• 8500' - HS 50 cm
• 8800' - HS 72 cm

Snow felt warm dense and only lightly faceted. Overall promising start to the season.

Lionhead, West Yellowstone

Barely enough snow at Ski Hill (el 8000') to get there on sleds. Also, very faceted with some surface hoar mixed in midpack. Overall, less snow and more faceted.

Toured up to below Hyalite Peak yesterday morning before the storm. Despite all of the wet snow down low in hyalite, we found a dry snowpack beginning around ~8400’. Around 11am, winds really picked up in the alpine, with constant spindrift coming off cliffs of all aspects. We found lots of wind-affected snow, mainly scoured with the occasional 2-inch wind skin, but the wind was swirling in every direction and we couldn’t pinpoint an exact aspect being loaded.

In areas where the snowpack was deeper (>60cm) hand pits and probing into the snowpack revealed a fairly uniform structure, while thinner areas of the snowpack had more faceting. 
 

The trail to hyalite peak is thin in many spots, but this storm should make the approach much better.

Localized collapsing and cracking yesterday on the upper slopes of Mt. Henderson, SW aspects.  HS ranged from about 30-75cms.  

Snowpit attached from a SW aspect about 9700', HS 50cms, ECTN9 @ 22cms (1-2mm facets above MF crust).

Toured up lick creek on Thursday morning. Mostly Cloudy, pretty warm around 37 degrees. Wind was gusting fairly hard at the ridge from the SW and had deposited and compacted lot of snow on the top of the NE Bowl. Dug a quick pit around around 8000' on the NE side of the ridge. Snowpack was about 60 cm deep and a quick compression test failed around CT 24 on near surface facets about 4 cm from the ground. The block that failed was a cohesive slab about 50 cm thick.