Snow Observations List

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." 

Did the tour de Yellow Mules and today and found some amazing pockets of riding. Tricky riding the wind blow snow though, the snow would be supportable to the slab/old snow, but found some pockets where you’d break through and submarine into the facets at the bottom. Ski tugs got us out. 
 

The wind had definitely been moving things around, signs of decent loading and some avy activity today, kind of where I thought we’d find some action. See attached photos. Noticed a small 8-10” wind slab pocket on the way in, looked like storm load but could have been sled triggered from the top. Found a bigger pocket that had pulled out on steeper terrain in the 1st Yellow Mule no tracks around since we were the first in there. Both were N to NE facing which we had flagged for ourselves due to the wind direction during a post storm. We were suspect of the east side of the compass from north to south. 
 

We chose to play in the flats today, kept slope angles low, and stayed out from under avy terrain - Still had a blast. Didn’t dig today (sorry), but storm totals listed seem pretty accurate. Honestly, I expected a bit more action today, but I got enough info from those two spots to be pretty conservative. 

Skied the second meadow this morning. S1 to S2 precipitation while we were in the area; cloud ceiling was around 8000' around 7am and lifted to ~9000' by 9:30am; calm winds. Ski tracks from yesterday had ~2-6" on them. Snow was deep and dry; no signs of avalanches or instability were observed.

Toured up the ramp at around 4 yesterday, snow was still falling heavily. Counted 4 or 5 natural storm slabs breaking mostly within the new snow. A skier before us triggered a slide in the chutes on a ski cut. I struggled to find a clean interface where the storm slabs were breaking on a few hand pits, mostly just a lot of fresh snow. 

There was a natural avalanche on the landslide face above quake lake. The avalanche failed on a weak layers near the ground and broke several hundred feet wide. 

From the phone message: A skier on the south side of Bradley's Meadow triggered an avalanche and was caught and carried by the slide. Thankfully, everyone was okay. 

Around 7 p.m. Monday night, a few miles up Portal Creek, triggered from bottom of slope.

Small wind slab in hyalite at the start to champaign slot, 7600’, WNW, ~8” crown

We were ski touring on the SW side of Mt. Henderson today, and noticed a large (natural?) avalanche on the NE aspect of Henderson.  First observed at around 1:15pm.  It appeared to be very fresh, possibly from a remote trigger this morning.  

2 photos attached.   A NE aspect, around 10,000'.

It looked to be 4-6' deep and about 500' wide.  And it failed on snow at/ near the ground.

Weather:  today alternated between heavy snowfall, and patches of sunshine.  Temps in the low/ mid 20's F, and calm winds.  A very nice day for ski touring.

No other avalanche activity observed in Miller Creek.

We experienced a couple of large collapses on westerly aspects/ in wind affected terrain around 10,000'.

We toured into Carrot Basin and Sage Creek this morning. The storm ended and skies were broken by 1000. The spx is about 1M deep and the surface conditions are soft and excellent in most areas with wind effect along the ridges. At about 130 we moved from carrot to sage creek and notcied three small and one large avalanche along cabin creek divide that were not present earlier in the day. Most looked remote and were isolated pockets (R1/D1). As we rounded the corner into sage there was one fresh larger slide (R2/D2) at about 9,400' on a NE facing slope. It appeared to be natural (remote?), failed at the ground and was about 200' wide and ran for 200' the crown was 2-3' deep.

From email: "Skied in Sheep Creek today. Still a little lean. Surprised to only see one D1R1 soft Slab on steep north facing slope. No other avalanche activity seen on Miller Mountain, Mineral, Sunset and Republic Mountain. No cr/co." 

It was still snowing heavily when we arrived at the Beehive Basin trailhead this morning. We noted about 12-18" of new snow and winds blowing from the NE. It only took 20 minutes of skinning before we triggered a small avalanche in a terrain trap from a flat bench above. This slide (R3 D1) broke 150' wide, about a foot deep, and filled the creek bed below.

As we continued up the basin, we pulled off just south of Tyler's and dug a snowpit in a protected meadow at 8446'. Our snowpit (HS 130) gave us clear, unstable test results: ECTP 10 and 18. Propagation occurred at the storm snow interface (10) and on the faceted persistent weak layer close to the ground (18). Our snowpit was a great piece of data, but, after triggering an avalanche moments before, we had all the feedback we needed to stick to a conservative travel plan. We chose to stay in the basin and give a wide berth to slopes steeper than 30°. 

Once this period of active loading ends, the storm snow instability will settle out relatively soon. But we are not forgetting about the persistent weak layers that are still lurking at the base of our snowpack.