Snow Observations List

Remote triggered this avalanche at Lionhead. We were snowmobiling to the left of where the avalanche occurred. No one was caught.

Coordinates: 44°43'36.8"N 111°19'05.0"W

Today, during a level 1 avalanche course north of Cooke City, we did a total of 7 ECTs north of Companion Lake. We did 4 ECTs at 9640ft, two on a NW aspect and two on a SE aspect. These were all ECTNs in the mid 20s. We did 3 more ECTs on a north facing slope at 9380ft. Here we got two ECTXs and one ECTN 25. The buried surface hoar layer from early December was visible in every pit, ranging from 90 cm to 105 cm deep. The deepest snow we found was 185cm. 

Toured up the ramp this morning, found between 3-6" of new snow on the skin track, winds were fairly strong from the north/northwest and moving snow. Snow was falling heavily for the duration of the tour. As we made our last switchback in the ridge line meadow (8500ft directly east facing) near the top of the ramp, we triggered a wind slab. It propagated about 200 ft wide and was 3 ft at the deepest point. Interestingly on the edges and near the bottom (downhill side) of the slab it was only a few inches deep. It broke on the interface between the wind loaded snow and the light and dry snow we received a few days ago. When we entered the upper meadow there was no evidence of tracks from the day before. Further down the ramp we found cross loaded rolls that produced shooting cracks and collapses, and active snow loading from the new snow and wind. A half hour later on our ski down, the skin track was partially buried by new snow as we exited the area. 

A small slide was remotely triggered by the second skier catching up to the first skier.  We were skiing mellow terrain on the east side of a small ridge and remotely triggered the slide at a roll over point on the north aspect of the ridge.  Prior to skiing we conducted an extended column test on a near by north slope with good results but kept our path mellow do to some wind affect areas we noticed on the west side of the ridges. We skied to the debris pile after the slide stopped to take a picture and would estimate it broke 30 cm down at the base of the new snow over the last week. 

Saw a small recent looking storm slab avalanche that appeared to be naturally triggered above the road on a south facing slope around 6000'.  It ran all the way across the slope ~30' wide and  ~4" deep within the recent snow.  The snow didn't move far enough to reach the road.  The slope was quite steep-- we didn't measure but I'd estimate 40*.

We also had localized cracking around our skis with planar breaks on that interface throughout the day, as well as a shooting crack when a member of our group jumped on a south facing test slope.  On our way back down we saw an even smaller (~10' across) avalanche on a SW facing creek bank that appeared to be triggered by another party as a test slope.  Both of these test slopes were steep and we had no results on two other, less steep slopes.

Little Ellis now has (barely) enough cover to be skiiable (at least up high - still marginal lower down). Dug a pit on the NE aspect 100 yard NE of the summit. Found unconsolidated snow all the way down to the ground (roughly 36" deep). Negative ECT. 

We rode to the divide between Cabin and Teepee Creeks and then the fog/clouds set in and we couldn't go higher or further out.

From the moment we left the trail there was WIDESPREAD collapsing all day long. Snowpits were consistently 3-4 feet deep and the weak layer usually a foot above the ground. At higher elevations, I suspect that the weak layer is closer to 2 feet above the ground. Because of the widespread collapsing and very bad visibility, we were hyper-aware of slope angles so that we didn't inadvertently get on or under avalanche terrain.

Small slopes at low elevations were avalanching including some along Hwy 191 in YNP. It's always a bad sign when road cuts are avalanching. 

We stayed away from ALL AVALANCHE TERRAIN.

The good news - the powder is incredible, the coverage is excellent, and this snow is exactly what we need to heal the weak layer. Unfortunately, avalanche conditions have to get worse before they get better.

Quick late day trip up to Goose creek meadow to check coverage. OVC sky, L wind, S. Limited vis. HS 60-80cm at ~7400'. Probing showed a very weak pack, weakest below the last week's snow. Some prev wind redistribution, areas of 90 cm. 

Collapsing, localized. 3 audible collapses when poking around well off trail and in unskied areas~7300'. ENE aspect off ridge. 2-3m radius, HS 80+. Seemed to need some prev loading to show instability. No time to investigate but likely collapses were between the last week's snow and  the Dec drought layer, which probed very weak.

3-4 foot crown about 100 yards wide on East face of sheep mountain. 

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.