Snow Observations List

We were in the Beaverhead Mountains, mainly below Italian and Scott Peaks. We found various weak layers towards the top of the snowpack in places and in other places, completely bottomless pow approx 3+' deep. The weak layer areas the top 2" was breaking and sliding right around that 30 degree mark. We used Fatmap app to plan our route to the summit and worked our way around most 25-30 degree angles. Once we pushed that 30 degree angle that top 2" would release. In this area we observed the top 2" was hard like 1F or P hard, 4-5" of Fist or 4F, then another layer of 2" of P, and facets for about 20/30" to the ground. In the wind blown areas the top was almost solid, very hard and icy. 

Not good riding, but we did it.  

Observed this cornice fall triggered slide morning of 1/19/23. It was not there the previous morning which was sunny and clear. Photo: GNFAC

I dug one pit at 8200’ NE aspect in Yale ECTX. Kevin was a little lower and around on the east side of Sawtell, he felt a big wumph. He didn’t confirm what layer, but this is probably your buried SH.

Today we toured up Storm Castle Ridge with hopes of skiing the 19th Street Couloir. On the approach we were able to trigger small (2-4") wind slabs on most lee aspects, these slides ran fast and far for their size. We dug a pit at 9200' on a North aspect and we're able to identify the surface hoar but had no results on our ECT.  With 2 spotters I dug an ECT 10m below the top of the 19th Street Couloir and got and ECTP12@ 35cm below the surface. The slab was 35cm thick, pencil hardness and failed on faceted snow; the buried surface hoar found in most other pits was not present. We bailed to the opposite side of the ridge and enjoyed some wonderful burn skiing. 

Small avalanche broke while descending to less exposed areas.  Approximately 80 yards wide, 18” deep.  Slid for approximately 90 yards from crown.

A snowboarder triggered a shallow avalanche (estimated 4-6 inches deep) on Saddle Peak in the new snow. The slide was as the snowboarder dropped off "Quarter Saddle" and a second pocket propagated above him as he traversed out of the first slide. 

Another slide was seen from the highway in Argentina Bowl. This slide appears to be a shallow soft slab that ~50 ft wide and ran ~500 vertical ft.

From IG: Some people got something to run long off the south peak. People were center punching Argentina and north saddle without consequence, but the wind slabs were generally dense enough to propagate but not so dense that they weren’t easy to trigger.

From IG: Sent attached screenshot and video.

Natural soft slab release likely in the last 36 hours. Seen from in-bounds at the Yellowstone Club. Avalanche location at 45.2116512 N 111.47811 W at the headwaters of Muddy Creek. 

Observed a point release that appeared to have stepped down. This occurred SE of the “rip curl” zone. We also noticed significant sun effect and a warming trend throughout the day. 1/17/23

Dave and Doug rode around and saw multiple natural and 1 sledder triggered slide on Lionhead. Some were thin and just involved news snow and others were deeper and broke on the buried surface hoar layer.

East aspect, 10,300.  Estimated to be about 75' wide.  Likely occurred yesterday, Jan. 17th.  

Wind loading from last storm snow. Large surface hoar formed on all aspects. Also noticed 1-2cm settlement around trees on northeast facing slopes.

We crossed Hebgen lake near the dam and skied in the trapper creek area.

About 2 inches of new snow - consistent from the lake to the ridgeline. No signs of instability or avalanches observed (we didn't see the small slides triggered on Sunday). Dug on a SE aspect at 9000 ft (just below the ridge). Found the surface hoar 1 ft down (ECTN17) and fist hardness facets at the ground. Was surprised not to get propagation (maybe not enough slab in this spot?), but stuck to our initial plan and avoiding steep slopes anyways. 

New surface hoar is growing on the snow surface at all elevations, in places feathers are up to 1 cm. 

We rode to Arange Peak and dug a pit (HS 210 cm, S facing, 8800'). We found the SH/nsf layer, but it did not propagate, It was a good 2 feet under the surface. We then rode and dug 3 more quick pits and either didn’t find the SH or had ECTN or CTN. We saw no avalanches and a rider who was near Mt. Jefferson 2 days ago also saw no activity. I am still very leery of the SH and believe it survived on a few slopes and acted accordingly, i.e. no riding steep slopes.

Noted a couple of fresh slab avalanches out there today.  Both were on northerly aspects around 9300'.  Photo of one attached.

We skied up the northeast face/gully on Ross Peak, and dug a pit just under the summit of the east face, just before the slope angle increased to reach the summit. This was the last part of the approach to the Banana couloir. We noticed variable snow depths on the way up, and intermittent wind slabs of about 4 inches deep on the way up. Our pit resulted in an ECTP19. The propagation went the full plane of the column, and broke about 8 inches from the ground on a harder layer with sugary snow above and below it. Other than the harder layer, most of the bottom of the snowpack seemed loose and faceted, with about a foot of powder on top. We ended up turning around before entering the steeper angled terrain.

Mostly facets throughout snowpack on east aspect of Divide Peak. Dug in search of buried surface hoar, none found. Melt-forms and lower density snow found between 85-81cm. ECTX. 

Dave and Doug rode around and saw multiple natural and 1 sledder triggered slide on Lionhead. Some were thin and just involved news snow and others were deeper and broke on the buried surface hoar layer.

Our avalanche course toured up to the west ridge in Beehive Basin.

We dug four side by side hasty pits on an east aspect at 8740'.

HS 115 cm

HST approx. 8-9 cm

ECTX x 4

We were on the hunt for buried surface hoar. With no fractures in our ECT's to help locate the layer, it's hard to say whether the layer was or wasn't present, but we couldn't find it. Other than a MFcr down 30 cm with some associated near-crust facets, the snowpack was largely right side up with F to 4F above the crust and 1F to P below all the way to ground.  Basal facets comprised the bottom 20 cm and were 1F to pencil hard.  

The new snow was not particularly well bonded to the old snow surface.

The other half of our group dug on a westerly aspect at approximately 8500' off of the east ridge and found buried SH down approximately 30 cm. It was clearly visible in their pit walls. ECTN's on the SH layer in their pits. 

Snowmobiled to lower rock island lake and ascended to 9200ft. Mostly sunny skies with no wind. No avalanches observed, no collapsing, minor cracking right around skis in wind affected areas 4 inches deep. Dug on due N aspect. HS = 120-150 cm. Soft surface 4-6 inches. 1 finger hard layers with rounding facets in between with 2 layers of concern about 1 foot down and 1 foot off the ground where 4F rounded facets are sandwiched between harder layers. CT6 Q2 down 4 inches on old snow surface. CT 23 Q3 on basal facets. ECTN 6 4 inches down, ECTN 29 about 1 foot down (consistent with last weekend observation in this area). Stubborn old snowpack right now with lack of significant new snow or wind and recent warm temps. Still poor structure in areas where snowpack is thinner, however where it is deeper seems facets are healing.

I skied south of Quake Lake today, and we took the time to dig a couple pits along the way. We dug our first one on a west aspect at 7250’, and picked a big meadow to see if we could find the buried surface hoar we found above Hebgen yesterday. I jumped off my skis like I was jumping into a lake, and sank straight to the bottom. Total snow depth was 110 cm, and the surface hoar was not nearly as obvious as it was in our pit above Hebgen. An extended column failed at ECTP12 on the surface hoar, which had much smaller crystals than what we found yesterday. Still, it is not very trustworthy. The pit also failed at ECTP21 on the interface with large facets 20 cm off the ground.

A second pit on a west aspect at 8600’ also failed at ECTP12 on buried surface hoar, but total snow depth was 125 cm and supported our weight well without skis. We observed numerous point releases that entrained enough snow to possibly knock a skier over, but none stepped down and fractured as a slab.