Snow Observations List

Starting at Bear Basin trailhead toured into Middle Basin topping out at the highpoint on the ridge.  We saw no signs of snow instability throughout the day.  The temperatures were warmer than expected in the morning, the afternoon brought cooler temps and a little snow.  The skiing was suprisingly good in places and wind affected in others.

Today we had a question that needed answering: What is the distribution of the surface hoar? We dug in 5 places on different aspects and elevations and the answer was, “Everywhere.” But the SH is small and you can’t see it in the pit wall. It is buried about 20-35 cm deep. It will need more weight on it to get it to go. If a person was not looking for it it would be hard to find without an ECTP or Q1 fracture. I’m worried about areas with a slightly beefier slab, like what we found in Henderson Bench yesterday. Propagation and human triggering seems possible in these spots, but they are few in number. We found some thin spots and felt the sled bog down in the facets, which is issue #2. Triggering avalanches from thinner areas is still on our radar and may be for most of the winter.

From Facebook: High Mountain Adventures snowmobile rental reported one of their renters triggered a slide on the waterfalls (Mt Jefferson/Sawtelle).

Photo attached of a fresh natural avalanche, just south of Cooke City today.  It appears to have run last night or this morning.  (photographed at noon)

we skied up to 9230 on a south slope of Miller Ridge in sheep creek basin.  Intermittent clouds and sun, no wind.  Much wind affected snow, cross loading.  2-4 inches of fresh snow.    HS at 9000 was 100-110cm.  Started finding wind slab on rotten base at about 8900 then at 9200 where slope steepened we observed 3-5 foot shooting cracks and turned around.  Slope was 27-35.  Had climbed thru whitebark regrowth from 88 fire.  

We had good visibility and rode to Lulu to look at an ava that was triggered yesterday, a small cornice collapse. The one on Chimney Rock (triggered 2 days ago) was not big, but more indicative of weak layers at the ground. Chimney was 2 slides side-by-side, mid-slope, that likely went at the same time. These likely broke on facets near the ground. The snowpack was thin there. We then rode to Wolverine and Abundance. We saw a new snow slide on Wolverine in the deep cleft on the face. We dug on the shoulder of Abundance (HS 200+) and did not get anything remarkable in our stability test.  We then rode to Henderson Bench. There was one small slide off the Henderson ridge by the radio hut. We dug off the bench and got a surprising ECTP 11 on surface hoar buried 30 cm under. Crystals were not big (2-4mm) and you could not see it in the pit wall, but the ECT sure popped it out.

Snowboarder triggered this slide on a rollover on East Republic. Reportedly ran 80' wide, 1-1.5' deep. No one was caught.

There was 4 inches of new snow in Taylor Fork, and there was wind drifting in several places. We rode to the wilderness boundary to dig a pit. We were on a south aspect at 8,800’. HS 125cm (~4 feet), ECTN5 on surface hoar under the new snow, ECTN21 on facets 1.5 feet below the surface, ECTN 28 on facets near the ground. We rode past the Otter Slide to dig on a north facing aspect, and we had an ECTP5 on buried surface hoar. There was 6” of new snow on top of the surface hoar layer that propagated. While leaving Taylor Fork this afternoon it was beginning to snow. The additional snow in the forecast will likely make this surface hoar layer more reactive now that it is buried. Additionally, the poor structure throughout Taylor Fork could make the deeper weak layers more reactive.

We exited Bridger Bowl via the ridge and dug a pit at the top of Lazy Susan near The Ramp. It was 111 cm deep and full of facets. The lower half was facets, and the top was faceting, and there was surface hoar. We had ECTN17 and 18 at 79cm. Felt weak, but generally stable. You could trigger an avalanche somewhere, but danger is decreasing without new snow and wind-loading.

Snowmobiled to 8200ft then skied up to 9000ft. Dug a snow profile to ground on NE aspect at 8800ft. Height of Snow was 120cm (4 feet). Multiple weak layers in the snowpack including one about a foot down and a thicker layer of faceted sugary snow in the bottom 2 feet of the snowpack near the ground. ECTN29 on a crust and small grained facets about a foot down from the surface, however that slab layer released when a shovel was put behind it with a sudden pop and very little friction, see grainy photo. Surface was faceting old powder which could be another weak layer when buried. Not very reactive in this spot at the moment likely due to lack of new snow in a while. However generally poor snowpack structure is not reassuring and will need to watch when this snowpack gets rapidly loaded by new snow or wind blown snow. 

Observed recent small wind slab avalanches under the ridgeline as well as one larger slide that broke on weak snow near the ground, likely cause by cornice fall. 

@ 7740' east south east aspect 20 deg slope we found HS 87-105cm, large grain faceted snow near the ground, ECTN 29 @ 55cm above Xmas crust. Saw multiple D1-D2 DL or unknown ( couldn't see crown) in ramp/ wolverine/ hourglass couloir. 

Skier unintentionally triggered and was caught in wind slab avalanche on the Y couloir in Sheep Creek Drainage. Skier was carried 10m before self arresting. The slide ran ~250m down and broke across the entire width of the couloir. There were no injuries and skied away. 

Yesterday we tested and skied a well-protected, NE-facing line above Blackmore Lake. There were strong winds during our approach and we observed evidence of wind loading on northern aspects. By around 2 pm, wind speed and wind loading reduced significantly. At our pit location, we observed a thin wind crust (1-2cm) that moved quite readily. This layer did not move during stability tests and did not propagate while skiing, but released readily while skiing. At the bottom layer of the snowpack, we noted that the grain size increased since our visit to the area last weekend, and the faceting in this layer was much more apparent particularly at the bottom of the layer (see photo). 

I am finding very solid snowpack in most areas. We dug one pit yesterday that exhibited two weak layers in the top 35cm and one near the ground. This was a wind loaded slope with HN 230cm. CT test did not fail. No evidence of surface hoar at this location. 9100 feet on a NE aspect.
At lower elevations I found evidence of surface hoar forming, but not necessarily on the snow, see photo.

We are entering a warming trend, which is generally healthy for the snowpack. The conditions are right for surface hoar development; however, I am only finding very isolated evidence of this. Something to keep an eye out for.

We have several weak layers in the snowpack that could fail causing an avalanche, likely a large deadly avalanche. It's hard to find places that exhibit reactive test results, but the evidence is in recently human triggered avalanches. We are not getting a ton of new snow and together with the mild temperatures this will create a strong snowpack over time. The places to watch out for are shallower snowpack areas where the persistent weak layer is easier to trigger.  

From IG 1/7/23: We dug a pit in island park back up Blue Creek on the Centennials side. South facing slope. ECTX

Toured into Hyalite basin and found evidence of what looked like an older and large slide on Hyalite peak. Intense wind scouring appears to have taken place, or the slide ripped to the ground. Ample evidence of wind loading and stripping throughout the bowl left us with enough evidence to turn around without digging. We skied lower angle trees out of the basin and then toured into Divide basin. We dug a pit on the sheltered shoulder of the typical skin track to divide peak and got an ECTx. Snowpack was well bonded and congruent to the ground on this specific E-NE aspect and slope Snowpack was about 100-145cm deep in total.

We toured into Beehive Basin for our level 1 class.  Widespread surface hoar up to 6 mm on west to south aspects (we did not tour on any other aspects).  Buried SH under the recent 7 cm of storm snow was present, though it was not fully preserved. Some feathers were still vertical while others were knocked down. Buried SH was reactive but not propagating long distances. Small, short cracks were observed on that layer in our tour. Wind-loaded pillows from prior loading were visible on much of the steeper western aspects off of the ridge, especially down low and in cross-loaded gullies. 

Overall, we were happy with the snowpack structure in our singular pit location, surface hoar not withstanding (see attached profile).  Snowpack was right side up and the basal facets were moist, beginning to round, and pencil hard. The ground was warm and soft (and a bit muddy) with a stout 2 cm plus ice layer. 

On the lower angle wiggles in the basin, the ski quality was quite good, and the powder was quite loud. 

Dug a hasty pit on E facing 23 degree slope at 8100 ft above Sportsman Lake. Overall snow depth 165 cm. Found all the familiar suspects including depth hoar, the Thanksgiving weak layer and two 1F layers between 4F layers in the top 60 cm of the snowpack. CT and ECT both produced no results. Temps were warmer in the valley, but didn't show signs of being above freezing above 7500ft.

We skied mellow terrain anyway and made very sporty turns on our nordic skis.