Snow Observations List

Observed cracking and whumping throughout the day. Towards the end of the day one of our riders remote triggered a massive avalanche on the North facing slope to the North of Yellow Mule cabin. The 3-4 ft crown propagated around 600 yards wide and slid on near ground facets to the bottom of the slope below depositing a very large debris pile well into the trees. 
 

No riders were caught and we inspected the debris pile after. Some of the touchiest avalanche conditions we’ve ever been out in. The meadows were riding nice, I would suggest sticking to them and well away from any steep slopes.

For longevity in the backcountry, base terrain selection decisions on indicators of instability rather than stability and consider the big picture rather than the small one. That is what we did in Beehive/ Bear Basins today (2/15). With an avalanche warning in place, a foot of new snow, a natural avalanche across the valley, and a snowpack that has proven to be reliably unstable this season, we ignored stable test results (ECTN teens and 20s) and absence of observed cracking/ collapsing. We executed our plan to avoid terrain over 30 degrees. Additionally, with the season's history of triggering avalanches from long distances away, we were cautious about traveling below steep slopes.

We met an avalanche class who were working on snowpits closer to the ridgeline. The group experienced one large collapse and had a number of test results that propagated on the weak faceted snow low in the snowpack. 

North facing, cross loaded, mid-mountain slope on an east to west running rib at around 9,600'.  Typically this zone is scoured by W-SW winds.  Mild to moderate winds and new snow of 10-12" sitting on an exceptionally weak base produced a natural release during the recent storm cycle, possibly early AM 2/15/24. The slide appeared to run full track, 800' +, taking out most of the north facing wall.

Sun came out for for a bit around 2pm when I was on top of Henderson Mountain. Got a good look at East facing Miller, South Face of Crown Butte, west side of Sheep Mountain and did not see any recent avalanche activity.  10-12"  new snow in town and on the mountain as of 2pm today. 

We took advantage of great visibility and rode in from Taylor Fork up to Sage Basin and then over the Beaver Slide and around Skyline Ridge into Cabin Creek. We saw three recent avalanches along the headwall of Sage Basin and one in Sunlight Basin. Two of the slides in Sage and the Sunlight slide looked to be naturals that broke a couple days ago. All of the slide looked to be 2-3 ft deep, breaking on the early season weak snow at the bottom of the pack. One of the slides in Sage broke ~700 ft wide. The other slide in Sage looked to have been remotely triggered by riders yesterday from ~100 ft away. 

Beautiful sunny weather and riding conditions today. No cracking or collapsing observed today.

It's going to be heads up as it starts snowing again. Expect to easily trigger avalanches if you get on or near any steep slopes in the next few days.

I skied above hebgen today, and was surprisingly the only one out there. The clouds opened up enough to see numerous 2-4’ deep slides that occurred over the past week, on slopes down to 29-30 degrees. Many started quite low on the mountain. There were several places where 27-28 degree slopes had shattered into cracks without sliding. 
I dug a pit on an east aspect at about 8200’, and found 130 cm of snow. An ECT failed at ECTP 29 at the interface of the basal junk and newer snow, about 90 cm down. Normally I would see this as an encouraging sign, but my pit today was purely academic and I skied dad pow all day. I did not experience any collapsing today, in stark contrast to the 2-300 collapses I got Nordic skiing around the hebgen basin yesterday. 

End of Forest Service Wall outside of Big Sky Resort boundary. 

We rode into Buck Ridge today and in First Yellow Mule, we triggered an avalanche 100' away from a flat meadow below. This avalanche broke several hundred feet wide and 3' deep on weak faceted snow low in the snowpack. This was right next to a slope that we had remotely triggered weeks ago on January 22nd, observation here. We knew conditions were dangerous and chose not to travel on or near steep slopes, but triggering an avalanche in the first hour of riding didn't make us feel great. Similar to what Dave said in his video we left here feeling as though the danger was higher than we thought. From here we continued on towards Muddy Creek and along the way saw a few natural avalanches in McAtee Basin and a small recent rider triggered avalanche in Third Yellow Mule. 

While signs of instability later in the afternoon were not obvious the glareing red flag from the morning had already set the tone for the day. Getting on or below terrain steeper than 30 degrees was not on the table and will remain off the table until conditions improve. 

Observed a recent avalanche on Henderson Mountain East aspect today. 

Pro 1 class pits and field observations:

Bottom Line: Still isn't looking good.

We toured out in Beehive Basin, conducted stability tests representative of of adjoining terrain. In 5/6 test pits we found the persistent weak layer is still problematic if you are going to get your skis or sled underneath the upper melt-freeze crust. There was also dramatic spacial variability of layers and reactivity even within a 50m x 50m area. This led us to believe that although there are tracks on the mountain, the button is still hiding waiting to be pushed.

The new storm layers have very poor bonding and are also capable of propagation. 

We observed two natural (assumption) slides one ridgeline back on lower Beehive Peak, leading us to conclude there is a possibility of small to medium size avalanches within the new snow layers in addition to the massive sleeping dragon at the bottom of the pack.

Got a whumph descending the ridge from little Ellis on the ENE facing slope just below the ridge around 7000'.

Saw some small cornices but snow was soft below the ridge. Hopped on the flat ridge top adjacent to a wind lip and got no result.

We rode into the Throne today in the Northern Bridgers. Our objective was to get to the top of the throne this time and to see what the warm-up in early February did. We felt that without signs of instability and good travel practices, this was an appropriate goal with wind-loaded terrain being off the table. At the bottom of the Throne, we discussed that if we saw signs of instability such as cracking and collapsing it was time to turn around. About halfway up on an east-facing slope at 8000' we dug a snowpit to test for instabilities. What we found is that the warm-up didn't change much, and found dry faceted snow below a stout crust that did form. Stability tests were reasonable with a score of ECTN 21 and we felt comfortable continuing to the ridgeline above. On the backside of the ridge, we were able to easily trigger small avalanches (1-2" deep) in the new snow. While walking on the ridge we felt a large collapse and saw shooting cracks behind, below, and above us. This made us both jump a bit and was an obvious sign that it was time to turn around. We pulled the plug once again and began skiing down, but not before kicking off a few more loose snow avalanches on the north side of the ridge. 

Here's what we took away from this. First, the snowpack is still very weak and it will take more than just a short warm-up to improve stability. Second, areas where new snow has drifted into thicker slabs are concerning, and triggering an avalanche is likely. Third, new snow is bonding poorly to the old snow surface and as snow continues this new snow will be sensitive to human triggers. 

Skied the whitebark glade on Flanders and got several whumpfs at the mid and upper elevations. Light overnight and continued wind loading. There was a recent avalanche that appeared to be a wind slab with decent propogation on a north facing rocky slope. Visibility was too poor to get a good look or photo. 

No details, came upon them while riding and making observations of the terrain. One was North-Northeast, the other was North-Northwest facing. Across the drainage from each other. 
Also, notice three other small avalanches on a west facing slope, about two miles east of the first two. All five were on slopes well over 30. In the centennial mountains, close to the continental on the Idaho/Montana border. 

No details, came upon them while riding and making observations of the terrain. One was North-Northeast, the other was North-Northwest facing. Across the drainage from each other. 
Also, notice three other small avalanches on a west facing slope, about two miles east of the first two. All five were on slopes well over 30. In the centennial mountains, close to the continental on the Idaho/Montana border. 

From email: "Natural avalanche from yesterday evening or last night.  

North facing aspect, with an interesting 3 tiered crown beginning around 8900'."

We took our level 1 course up to the ridge between Beehive and Bear Basin. Skies oscillated between overcast and broken as light snow fell throughout the day with little to no accumulation. Winds were generally light, and no snow was being actively transported.

We descended a low angle east aspect down to about 8500' and found quality surface conditions and fun turns.  This week's snow comprised the upper 35 cm of the snowpack, was right side up, and generally well-bonded to the new/old interface below. Hand shears, up-track tests, and small test slopes were non-reactive.  We avoided any sustained slopes over 30 degrees and we saw no obvious signs of instability during our tour.

We dug two quick pits and performed an ECT in each. We found very similar poor structure in both pits and both ECT's propagated across the column within a layer of soft facets about 18" below the surface.

East aspect @ 8500', 28 degree slope

HS 90 - ECTP24 @ 44 cm 

90-55  F>4F>1F - This week's snow

55-50 - P - Rounded Grains -  January snow

50-35 - F - Facets

35-33 - 4F - Decomposing Crust/Facets

33-20 - F - Facets

20-Gnd - 1F - DH/Facets

East aspect @ 9100', 12 degree slope

HS 88 - ECTP11 @ 43 cm within a layer of fist-hard facets

Very similar structure to above, except for a 2 cm pencil hard MFcr at the interface below this week's snow capping a few cm of pencil hard rounds from January.

Fist-hard facet layer began at 47 cm and transitioned to 4F DH at 20 cm, with large and striated crystals visible to the naked eye.

On Mt. Blackmore we dug a pit on the east face near the ridgeline. We measured 10-12" of new snow that fell over the last week, equalling 0.7" of snow water equivalent. In the trees and less wind affected areas there were 14-16" recent snow, but we did not measure SWE there. In our snowpit on an east-facing slope at 9700' we found this new snow sitting on 2' of faceted snow, showing us that the structure is there to create avalanches. While stability tests were not remarkable with scores of ECTX and ECTP29, we did not feel like stepping into avalanche terrain was an appropriate decision for two reasons. First, we know the snowpack setup is capable of creating large avalanches and new snow will increase the likelihood of this. Second, recent wind has drifted the new snow into thicker denser slabs that will add additional weight to already unstable slopes. We saw clear signs of wind loading with fresh cornices forming at ridgelines and pillows of wind-drifted snow forming at the top of rollovers. While skiing out my partner and I both noted that the snow felt unsupportable with our skis breaking through to the facets below. We also discussed that as more snow and wind come this week dangerous avalanche conditions will continue to exist.