Snow Observations List

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), 1 on Henderson in the big east facing slide path (R1-D2) and 1 on Old Man Ray's on Republic Mtn (no photo). We also saw 4-5 smaller wind slabs (R1-D1). The larger avalanches 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. In a snowpit on West Henderson we had ECTP23 and ECTP24 about 2 feet deep on a layer of 1mm facets. Below that the snowpack seemed generally strong. Based on the recent natural avalanche activity, this is a weak layer we will have to keep an eye on going forward, and it could produce human-triggered avalanches for at least the next few days.

Today our party of three skied Blackmore peak, knowing beforehand the new snow and wind would keep us off the standard East Ridge to the summit, but still wanted to ski a lap on the lower section of that same ridge. Beforehand we were able to easily trigger shallow, short running windslabs by knocking down small cornices. We then headed up to the summit from the largely low angled SE sub-ridge and skied wind scour back to the trail. This lower angle terrain whumped on us a few times, whenever we stepped out of the trees, a hasty hand pit showed a thin sun crust under the new snow interface to be the culprit. Thought the attached picture may help some folks decided on weekend plans. Thanks!

We rode near Cooke City where more than 20" of snow has fallen since yesterday morning, and more snow is expected tonight. This new snow creates dangerous avalanche conditions and we expect natural and human-triggered avalanches over the next 24-72 hours. While touring on skis we experienced a couple large collapses. 

At our snowpit, HS was 55-60” (140-150cm), New snow was 21”=1.2”SWE, and we had ECTP19 and 23 above a melt-freeze crust that formed last week, buried 26-28” deep (6-8” below the newest snow). The snowpack below the crust was small rounded facets (0.5-1mm) and average 4F to 1F hard. Snowfall was 1-2cm/hr. Wind was gusting moderate to strong and seemed like it was hitting harder above us, at ridgelines and starting zones. 

ECT Results - ECTN 11 at 55cm

Location: Bacon Rind, Skillet, about the center of the upper skillet meadow, approx 100' below the ridge line N 44deg58.3210' W 111deg05.8191

Weather: Temp ~25F, cloudy, moderate snowfall, winds mild in trees, moderate winds on ridge line

Heading: E (110deg)

Elevation: 8890

Slope Angle: 34deg

Total Snow Depth: 110cm

We observed about 50-55cm of new and wind deposited snow on the eastern aspects that we assumed had been from snowfall/wind over the last week.  This new snow layer was generally F hardness.  The new snow was weakly supported by a 3cm thick faceted layer.  The ECTN 11 result was due to this faceted layer collapsing.  The remaining base snow pack was 50-55cm thick and approximately 2F hardness.  We repeated the test 2x in the same pit by digging back and retesting, the faceted layer failed both times without propagation, the ECTN 11 result was clear in the second test, the first test was hard to interpret but allowed us to identify the problem layer.  ECTX result on the remaining 55cm thick base snow layer. 

Wind loading produced dense snow drifts that were prevalent along the ridge line, but in the protected east aspect meadows below the ridge line there was much less evidence of denser wind loading.  We did not observe any whoomping either skinning up or skiing down or any signs of natural avalanches.   We skied the east facing short meadow just south of the skillet, then skied the SW facing meadow to the west of the ridge line and lastly skied the skillet to the valley floor.  As someone else reported earlier in the season the bottom half elevation of the run to the valley floor has many exposed downed trees and hidden hazards, personally I won't return to ski there until there is more snow depth at lower elevations.  The SW facing meadow had a supportable suncrust layer, with a mix of 6"-24" of wind drifted new snow depth, depending on where/how the wind had scoured it.

Pretty solid conditions yesterday. Some drifting occurring at the top but better then expected. Pit showed a right side up pack with the usual small layer of facets at ground level. ICT 25, slight but stable wind packed layer on top 2 in. Decent felt really good and conditions felt comfortable enough to ski any aspect on Ellis.

Good skiing on the backside of Lick today.

Dug a test pit on the backside out of curiosity and found 95cm of snow and a ECTN16 score @ 31cm down.

Dense slab that fractured on top of a 1F crust.

The snowpack turned out to be more stable than I had expected. 90cm at elevation with descent cohesion. 10cm of new snow. Compression test resulted in a CTN. Extended column test resulted in ECTX. I am still wary of some wind loaded drifts that could crack or collapse but didn't find any. There is a weak faceted layer about 20cm down that could become a problem with a new load of snow.

90cm at elevation with descent cohesion. 10cm of new snow. Compression test resulted in a CTN. Extended column test resulted in ECTX.

We sledded from Buttermilk to Ski Hill and dug a pit at 8000'. Snow depth was 80 cm, ECTN15 on E aspect–no NSFs or surface hoar at the pit.

While touring up Lionhead Ridge we triggered a whumpf with a noticeable crack on wind pillows at 8500’. At the whumpf snow depth was 83 cm on the NE aspect with ECTP11– failed on a layer of near surface facets.

As the terrain below the ridge (to the east) became steeper, we triggered a loud whumpf at 8600’. At the whumpf snow depth was 105 cm on NE aspect with 2x ECTP11. This was on a well-defined layer of 4mm surface hoar 35 cm from the surface. All ECTPs were on NE aspects with new snow and wind load atop the layer. This layer of near surface facets and surface hoar is our primary concern, and triggering a slide in steeper terrain with this weak layer seemed likely today. 

Saw natural avalanche debris below the cliffs on the NE face of Fan from the resort. Tons of wind loading the last few days. Light wasn't good to get a clear picture. Looked like a few different smaller avalanches but could have gone all at once. 

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.

On a northeast facing slope at 9,100' near the ridge that divides middle and beehive basins my party dug a pit that was 65 centimeters deep, the extended column test had a score of ECTN 19 at 37cm. The layer at 37cm from ground appeared to be 5cm of sugary fist density snow sandwiched between layers of 4finger density snow.

We observed small shooting cracks up to 6 inches while traveling through freshly wind loaded snow near ridgelines. 

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. Tons of people touring up bridger today, many without backpacks/ beacon shovel probe.

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. 

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.

Skied bacon rind skillet & one gulley just south of it today

No avalanche activity, cracking or whumphing 

No wind today up to 9000’; no evidence of recent wind-drifted snow

No new snow; Snowed s-1 all morning with no real accumulation (trace)

Average HS 60 cm at Skillet ridge top (approximately 9000’); 70 cm max depth 

Faceted surface snow on cold aspects (skied well) and 3 cm thick crust on anything remotely solar

Dug one quick pit on E aspect at 8840’:

HS 60 cm

CT 13 Q3 down 17cm

CT 23 Q3 down 25 cm

ECTN 24 down 30 cm

Yesterday toured up Bacon rind on the spur just to the south of the Skillet, dropped west towards Ernie Miller ridge and skied two laps on the N end of the ridge. We travelled back to the car on the same route and skied out the skillet.

60-70cm HS observed on E aspect at the top of Bacon rind Ridge 

No Cracking or Collapsing observed all day 

Great supportable skiing, didn't fall through to facets anywhere 

pole probes felt uniform/generally right side up all day

1F zipper crust on the surface of anything solar

ECT Test Results

Location: 300ft below Lionhead Peak

Elevation: 9250ft

Aspect: East, 88deg

Slope Angle: 33°

Total Snow Depth: 115cm

Result: ECT 22, at 15cm deep (new snow interface).  At this location the top 10cm of new snow was loose, then 5cm of new snow formed into wind slab.  Remaining 100cm of snow ECTX, well consolidated, no visible layers, approx 2F hardness to the ground.  

Comments: Failure at the new snow interface seemed very spatially dependent.  We had an ECT 11 in another area. 

Skied multiple locations along Lionhead Ridge over 3 days, NE to E aspects.  Our observations were in line with the avalanche reports.  New snow was generally 15cm deep and weakly bonded to the existing snowpack.  There was minimal wind transport during this time along the more protected NE aspects along the ridge line, so the snow was not particularly wind loaded or consolidated.  Even so, there was multiple instances of small natural loose snow avalanches on steeper aspects or terrain rollovers.

Toured to the ramp and Bradley's Meadow on 11/25 around noon. Temperature was 45 F and wind was calm. Snow surface was moist 5-10cm deep on most slopes. The snow surface on shady slopes above about 8,000' remained dry, despite temperatures above freezing at all elevations.

I dug one pit at the top of Bradley's Meadow where it is moderately wind-loaded on the south end, east aspect at 7,800', and one pit halfway up the Ramp on northeast aspect at 8,200'. Both were just over 2 feet deep. I had ECTNs below the recent storm/wind-drifted snow, on a layer of small (0.5-1mm) faceted crystals. Lower half of snowpack had layers of 1-2mm facets, but supportable and generally stable for now. 

Skied out to the head of beehive basin for a fitness / recon tour. Made it about halfway up the head wall to the pass between Beehive and the Mirror lake basin. At lower aspects boot top powder with surface hoar predominated with patches of breakable sun crust. Higher in the basin (2800-2900m) south facing aspects were thin, windblown, and sun effected. Ski conditions were completely breakable sun crust by apx 5pm. Lots of moving snow on south facing aspects. I did not dig a pit. See attached photos. In the panorama, most of the chutes to the right of the arrow (4th of July couloir) had slid, it looked like it was mostly limited releases from sun warmed rocks. I did not see any natural slides to the left of the arrow. 

Surface boar forming in sunny spots at lower elevations

Pin wheels coming down on south facing road cuts

Backside skiing was already getting heavy just after 10, reasonably heavily trafficked since last storm, someone ski cut just below cornice with no movement.

Front side has a supportable sun crust under the last 4" storm