Snow Observations List

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

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.

Next, we rode around the back of Fisher Peak to Lulu and dug on the southwest slope below the weather station. Here it was shallow, 100cm. There were weak facets near the surface, but no slab on top of them, maybe due to the southerly winds scouring it. Could become unstable if loaded from the north or with a lot of new snow. Finally, we rode up to the shoulder of Scotch Bonnet and dug on far south Rastas. HS was 145cm, we had ECTP22 and ECPT27 on a thin layer of facets sandwiched between two crusts 55cm off the ground. Despite the hard force, these collapsed dramatically and re-iterated the possibility of triggering a large, high-consequence avalanche.

There is windloading along the ridge line but the snow is pretty unaffected on the face. 

I dug 2 pits at different locations:

Pit #1: ECT N21 N28 

Pit #2: ECTX 

Both pits were on E slopes around 7,800 ft.  Overall feeling good with the snowpack there. It does have a slightly upside down structure but couldn’t get anything to fail.  

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.”

We rode from Sage Creek trailhead to the weather station. After we got everything installed, we headed to Sunlight Basin to dig. There was about 12-15 cm of new and wind drifted snow. On the walk to the pit location we noticed the snow was punchy. HS was 94 cm on the E aspect. We got an ECTP 13 on a layer of 2 mm facets 44 cm down from the surface. New and wind drifted snow put a substantial slab on top of this weak layer. After we dug our pit visibility improved, and we saw a R1-D1 across the bowl that looked recent. While sledding around the area we noticed faceted snow in the middle of the snowpack in multiple locations.

Skied in NE Yellowstone Park today near Cooke City. No avalanche activity to report (low vis). Localized collapsing. No cracking.

We dug on a SE aspect at 8500'.

HS: 102 cm

ECTP25 @ 37 cm above ground.

Frequent shooting cracks, collapses, and whoomphs on wind drifted snow just north of town on a south facing aspect at 8,100ft.

We skinned into the Divide Peak cirque to check out the conditions in Hyalite for the first time this season. On our tour we saw a couple of small R1-D1 slides that had broken within the new snow. At our first pit we saw HS at 124 cm with 10 cm of new snow. We had a ECTP 30 on facets 64 cm down from the surface. Next we dug on a SE aspect with a HS of 127 cm and 15 cm of new snow. We got an ECTN-3 within the new and old snow. More importantly, the wind was picking up throughout the day, and it was transporting snow. Our primary concern today was new snow, and in the next few days it will be wind drifted snow.

The snowpack is getting punchy and soft, especially around rocks. The faceting has been taking a bit of a toll even though the snowpack is - relative to many Decembers - kind of deep. 

It was very windy in the base aream, and there were strong southerly winds blowing all the way up past the top of Bridger. It looked like there was plenty of windloading in the usual areas for southerly winds (like that northerly-facing side of north bowl). Lots of plumes coming off the ridge, and Saddle looked like it was getting blasted pretty good. We are certainly thinking about a hardslab on top of facets in the future. 

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.

West facing slope of Woody Ridge in Republic Creek. ECTn 21 at 65cm with a 120cm snowpack (8,842ft). Observed sugary facets close to the ground that did not react in our tests. No shooting cracks, collapses, or obvious signs of instability.

Cut a wind slab from the top of the John around 2:30. 3-6” crown. 50-75’ wide. Ran down to the low grade below

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 when 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. 

Found facets sitting beneath a crust 60cm from the ground. Observed collapse on this layer in our pits but no propagation. 

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

Snow pack of 108cm on a 25 NE facing slope at 9,625'

Observed CT11 Q2 at new/old interface, 93cm, as well as an ECTN13 Q2 on what we believe to be a buried layer of surface hoar at 26cm. Also had some warming of the surface.

With the poor pit performance we decided to not ascend to the ridge and ski the intermediate terrain in the cirque, then out the drainage.

Here’s an avalanche we saw on December 2nd 2022 in cooke city on the north side of Henderson mountain just above lulu road.

I toured in Lick Creek yesterday and thought I'd share a few things we noticed. Hopefully they are helpful observations!

While the skin track was still relatively flat and cutting through sloping meadows, we noticed a small sun crust on a southern aspect. 

As we skinned through the front side skiing zone, we noticed evidence of wind affected snow. We found some strong layers that sounded hollow, sometimes underneath ~2 inches of snow. As we gained the ridgeline, the wind slab became more obvious. It cracked under my weight, but I didn't see any shooting cracks or distinct collapses.

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. 

Dug a pit at 8700' on a W aspect. HS was 70cm. We got an ECTP12 45 cm up from the ground at the interface between wind packed snow and a layer of .5-1mm facets and mixed forms. That layer made up the bottom 45cm of the snowpack in that area. 

Dug another pit at 8800' on an E aspect. HS was 115cm. We got an ECTP 14 50cm up from the ground on that same interface as described above. The bottom 50cm of the snowpack looked to be facets and mixed forms. The upper 65cm in that area was a mixture of different layers of wind packed grains that ranged from F to 4F hardness. 

Coverage on the descent is adequate, similar if not better than any point midwinter last season. Under skis, the snow in the burn/forest feels unconsolidated and very sugary.