Snow Observations List

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. 
 

Skied on Henderson mountain the afternoon of 1/16. Wind was calm, snowfall was light and steady through the day with 3-4" of new snow.

Dug a pit on the east side of Henderson at the ridgeline above Henderson Bench. ENE, 10,075' elev. ECTP19 x3 on a layer of surface hoar buried 60cm (2 feet) deep. HS 260cm. There was an avalanche a few hundred feet north on an east-northeast facing slope below the ridge. It appeared to be snowbike triggered and 1-2+ days old. 150' wide and 250' vertical. HS-AMu-R2-D2-O. It appeared to have broke about 2' deep on that layer of surface hoar. There was also a more recent natural avalanche (less than a day old) on Miller Ridge, slightly smaller. SS-N-R1-D1.5-O and probably broke on the surface hoar layer.

The location of these avalanches and poor stability test scores is concerning as they are in exposed areas, implying the surface hoar will remain an issue on large, steep open slopes that will likely be heavily wind-loaded at some point.

Additional photo of a cornice triggered avalanche on Miller Ridge that broke to the ground, appears to be many days or weeks old.

We skied the Throne today, near the skin track, and down low and to the north. With only a couple inches of new snow and zero wind there were no signs of instability. Our pit in the north facing chute had horrible structure, with the bottom half very facetted, but didn't offer any results. The wind hasn't blown up there for quite a while, so there's plenty of soft snow hanging around. When it does blow, it won't take long to become unstable.

Toured into Alex Lowe basin today and noticed lots of point release slides. Most started as spindrift in the cliff bands along the ridge and gained more snow as they fell into the aprons. Skied a north and south facing couloir, ski cut at the top of both runs and got the new snow to sluff most of the way down. Didn't encounter any cohesive slabs, just lots of sluff sliding down.

Variable skiing at Lick Creek today. 2-3 inches of low density snow on the ground. Ski cutting on the north side wind roller produced very soft-soft slab results with little to no propagation directly under cornice. 4 inch soft slab on the interface. Ran about 20 feet with little entrainment.

It squalled out there around 12pm snowing S2 with little to no wind. That seemed to precede the squall in town by about 2 hours.

New snow and wind loading. On southeast facing slopes found 8cm layer of facets below melt freeze layer about 50-60cm below surface.

Today we toured up the east ridge of Republic Mountain and descended the southeast face. We observed about 10cm of fresh snow from the night before, and winds were very calm. Our pit results did not show any propagation at the interface above the faceting snow at the base and a quick shovel shear of this layer yielded a medium Q2 shear (see photos). A series of hand pits along the southeast face showed that the interface above the faceting base took some effort to move, but it would move with some force.