Snow Observations List

We observed many large whumps and shooting cracks while headed up the meadows of Cinnamon mountain today, several of which were large enough to shake nearby saplings. These collapses were likely triggering on the recently buried layer of basal facets. Conditions included warm temps, light SW winds, overcast to obscured cloud cover, and S-1 to S1 precip including steady graupel. Nothing particularly surprising considering the conditions in nearby areas, and we chose to keep our terrain choices conservative.

I skied above hebgen today, and found some encouraging signs. No collapsing on the way up, but I did get a few small ones on the way out below 7k. A pit on an east facing slope at 8800’ had 90 cm of snow, and I got a poorly-defined propagation at ECTP16 in the big, granular facets that make up the base of the snowpack. The newer snow slab was quite cohesive, although there is a thin rain crust that formed yesterday afternoon. The lake is currently a slushy experience. 

We rode up to Fairy Lake today and skinned to the top of the ridge between Fairy and Frazier basin. It snowed all day and visibility was limited; no recent avalanches were seen. One thing we noted was how little wind effect was present in this zone. Winds have been abnormally calm in the Bridger range the last few days, and many spots that are typically scoured, had full coverage. 

We dug a snowpit on SE aspect at 8550'. It was 5' deep, with nearly 21" of new snow. The base of the snowpack consisted of several decomposing melt-freeze crusts and facets. We did not get unstable test results in this pit. 

The snow that fell in the last 24 hours, came in upside-down (temperatures began cold, and ended warm). This was noticeable while breaking trail and skiing down. 

We did not note any cracking or collapsing. Despite seeing no red flags, we still recognize that the Bridgers have received 2+ feet of new, dense snow this week with little respite between storms. We stuck to our conservative travel plan and avoided slopes steeper than 30 degrees. Thankfully, there's tons of great low-angle powder skiing and riding to be had out there! 

Lots of 9''-10'' soft slabs running on the overnight snow/Thursdays density change interface, pretty much one side to the other on the East face. Mostly naturals, one skier triggered. D'oh!

While doing stability tests on the bottom 100 ft of the Bacon Rind Runout, we observed multiple "whumps" and a 10-12 ft crack about 5" deep on ~20° terrain. 

From IG 1/3: “Buck ridge today. NE aspect. Probably 100’ wide and at least 3’ deep. Looked like it was triggered by a snowmobiler earlier in the day.”

We rode over Daisy Pass and out to Abundance, then around Fisher and behind Scotch Bonnet, and back to Lulu Road. Visability was marginal with overcast skies and light snowfall in and out through the day. Wind was light to moderate with moderate gusts. Moving some snow from trees and along the surface, stiffening slabs. Snowfall rates picked up this evening. 

We saw three avalanches just north of Daisy Pass and one on Henderson Mtn. The one on Henderson was difficult to see the crown, but we could see the debris. Two of the slides north of Daisy were 2-3' deep and 100-150' wide and ran into thick stands of trees, looked like thick soft slabs/drifts of recent snowfall. The other slide was 1-2' deep and 300-500' wide, soft slab of recent snow.

We dug a pit between Scotch Bonnet and Sheep Mtn. on a sw facing slope at 9,800'. HS was 135cm (4feet). We had ECTP12 and ECTP26, both on a layer at similar height as the surface hoar has been found (1.5-2 feet above the ground). The weak layer was mostly 2-3mm facets w/ small cups and some signs of surface hoar on top of a melt-freeze crust. 

With a lot of recent new snow and more on the way, plus recent avalanches and poor snow structure, I expect avalanches will continue through the weekend. Choose routes that avoid travel on and below slopes steeper than 30 degrees.

We rode from Buttermilk past Ski Hill to the lowest portion of Lionhead Ridge, where the cornice line transitions to the wind-loaded rollover. There is a lot of new snow, and while there are still plenty of landmines, the riding is getting pretty good. No collapsing or cracking was observed. We dug on the northeast aspect on this mid/upper elevation slope and found the same persistent weak layer of concern buried 2.5 feet deep (Fist hardness surface hoar and facets). I was surprised by how sensitive this interface seemed given the depth (ECTP13). 

We then rode down and around to Denny Creek and up the local route to the lower meadow, where you first break out of the trees. We dug a second pit at the top of the first hill. Same story on this southeast aspect at 7900.' Fist hard facets and surface hoar buried 2.5 feet deep, ECTP13, no cracking or collapsing observed. 

I do not trust this snowpack. It is weak, it is failing with relatively small force given its depth, and the problematic snowpack structure seems to exist on every slope I have assessed this season in the Lionhead area. You might not trigger a slide on every steep slope right now, but you wouldn't need to ride many before triggering an avalanche. The structure seems uniform enough that remote-triggered slides are in play.

The CONSIDERABLE danger seems spot on with human-triggered avalanches likely on slopes steeper than 30 degrees. A forecast with continued snowfall will keep this snowpack on edge. 

Wasn't surprised to see this fresh human triggered slide in Beaver Creek when just around the corner was a previous one in 1st Yellowmule. 

Skinned across Hebgen Lake from the Kirkwood trailhead and ascended to the ridgeline above Trapper Creek. Snowpack was consistently 2-2.5ft deep throughout our tour. Got two small collapses on the ascent when we deviated from the established skin track. Dug on a SE facing slope at 9000 ft (just off the ridgeline) and got no results in an Extended Column Test (ECTX). The column smooshed under the shovel as I tapped, seemingly indicating that there wasn't enough of a cohesive slab above the weak layers. Got a larger collapse as we descended to a second snowpit site. Stopped and dug in the place where we got the whumpf. This pit was at 8500 ft on a south aspect. There was a thin melt-freeze crust over the basal facets here. This appears to be what gave the slab enough stiffness to propagate a fracture. ECTP12. Stepping out of skis you stepped all the way to the ground at both pit sites. 

With the recent load of new snow on weak snow near the ground, we developed a plan at the car to avoid all slopes steeper than 30 degrees and stuck to that plan. 

From text message: a snowmobile triggered a small persistent slab avalanche in the Taylor Fork on Tuesday. The rider was not caught. 

On a nearby slope, a larger avalanche failed 150 wide on weak layers near the ground. 

From Instagram story tag: there were many large storm slab avalanches in the northern Bridgers on Monday and Tuesday during the avalanche warning. 

Skied Maid of the Mist today. The only avalanches seen were small (<10ft in length) loose snow releases directly below small trees on north facing 35+ degree aspects at 9200 feet. Poor visibility generally limited views to a few hundred yards. A small amount of stiffening from wind was noticed on the snow surface on the way out of the basin, but there was little to no wind effect in the trees on the south side of the Maid. Ski conditions were fantastic.

This is from yesterday (202-01-01):

Low visibility, but we saw a few size 1 Dry Loose avalanches out of unskiable cliffy terrain.

Got one whumpf in a small willowy meadow near Ainger Lake. This occurred when one person took his skis off and sunk nearly to the ground. The rest of the group had already transitioned and stomped around in this spot without any reactivity.

In exposed lee terrain there was an unreactive windslab form the previous day (2024-12-31) buried by 5-10cm of new snow when we arrived. It snowed S-1 to S2 all day, winds were moderate gusting strong on ridges, but calm or light elsewhere.

Good powder skiing, no cracking or collapsing observed in the storm snow. 

From Instagram message: "Settling and collapsing on E-NE slopes above Hebgen. Full slope collapses and cracks, approximately 28 degree slope pictured." 

We skied around Sawtelle Peak today where there is a solid 4 feet of snow at 8750' where we restarted the snow depth sensor which is working now.

The good: We didn't see any recent avalanches, but we were traveling on foot and couldn't see all the terrain. The weak layer of snow that formed on the snow surface after Thanksgiving into early December is slowly gaining strength. There's also a ton of snow and coverage has improved dramatically. 

The bad: The weak layer of facets is generally in the middle of the snowpack and can be found on all slopes. The recent snow is the first big test of this weak layer, and it produced numerous big rumbling collapses on both an East and Southwest aspect. These collapses are an obvious sign of unstable snow and told me not to trust the snowpack.

Of interest: There are several thin rain crusts within the upper two feet of snow. You'll likely feel the upper most rain crust under your track but not under skis. The attached photo shows the most recent freezing rain event on the trunks of trees.

Small avalanche NE aspect near top of beaver. D1 natural trigger wind slab. Only observed avalanche from groomer trail. 

We rode into throne area to check it out today, left cars around 12pm

*Heads up the parking areas were unplowed and adventurous! *

In the meadows below the throne we saw HS 80cm -100cm around 6600-we mostly stayed on trail away from all the logs and stumps sticking out or only covered by storm snow. It was easy to trench all the way to ground in the lower meadow zone.

Skied on the sub ridge south of the throne HS 130-150 @ 7400. 

We saw numerous D1 dry loose avalanches and a few D2 slab avalanches between Ross and the throne, visibility was in and out so no pictures unfortunately. 

A handful of other riders were out, didn't hear of other avalanches from groups we talked to just lots of stucks in all the new snow. 

Over the last two days, 27" of snow and nearly 3" of SWE fell in the Bridger Range. Today, Dave and I toured out to the Ramp to see how the storm snow was shaping up. Visibility was limited at ridgetops, but we did see several storm snow avalanches just north of the Bridger Bowl boundary that failed yesterday. 

We dug a pit at the bottom of the Ramp on an E aspect at 7900'. We found 24" of new snow which had nearly doubled the snowpack, leaving over five and half foot deep (HS 171) snowpack in this area. In our snowpit test, we got propagation (ECTP 24) at the storm snow interface. We experienced no collapsing or cracking on our tour today. 

We decided to continue up the Ramp, but had a discussion before we entered the steepest portion of the route. Overall, our snowpit showed us signs that the storm snow has begun to settle out. Plus, we had not experienced any cracking or collapsing - but - as Mark mentioned two days ago in Cooke City, "a lack of collapsing doesn't override all the other red flags". Snow needs time to adjust from big changes, and 3" of water is an enormous load on our December snowpack. We chose the conservative option and turned, skiing excellent powder back into Bridger Bowl. 

From email: "We popped over to the recent avalanche on the east side and got a crown profile. Avalanche is NE facing, 10090. HS-N-D2-R4-O

Crown is 105 cm deep, breaking on surface hoar. Details are in attached profile 

Something noteworthy.. the slope angle at the crown is 30.1 degrees."