Snow Observations List

I skied on the east side of the Bridgers south of the ski area today. We dug a pit on an east aspect around 7300' and found 80 cm of snow with a similar structure to the more southerly parts of the advisory area. Well developed 2mm FC with a few DH cups sprinkled in made up the lower 40 cm or so of the snowpack (ECTP 21 on this layer) with the remainder consisting of 4F to F+ DFs. There was a razor thin "wind skin" I felt while skiing in more open areas below treeline but no major wind loading was present until at or near the ridgeline (pretty robust cornice development already for this time of year though). On our way back up just below the ridge around 7700' I felt a very large collapse that radiated out from my skis and shook some snow off of nearby branches. 

We skinned up Tylers and ran into a group of 4 who just wrapped up digging a pit. They had ECTP18 on the facets at 50 cm (HS 90 cm). We skied into Bear Basin in the Spanky’s area. We dug a pit that also had HS 90 cm. A few ECTNs but nothing concerning other than the thick layer of facets near the ground. Weak but not unstable…yet. The snowpack story seems more similar than not from West Yell to the Bridgers and Cooke. This layer of 2-4mm facets will be an issue with the next decent load, but until then the weakening continues.

Natural wind slab, likely triggered by cornice fall in the last day or two, on a NE aspect at 8500’. Propagated ~150’ wide and ran probably 300’. Slab thickness seemed to be 18-24” at the thickest. No sign of stepping down deeper into facets in the snowpack, although adjacent to this slide there was evidence of an older slide (previous to recent storm cycle) that failed deeper in the snowpack.

White Elephant drainage above White Elephant snotel @ 8,170'.

We rode in and toured up the Throne. We dug a pit low, on a northeast aspect at 7,850' and the snow depth was 63cm (2 feet). We had an ECTP27 break on 2-4mm facets at the bottom of the snowpack.

We dug a second pit on the north-norheast facing slope above The Throne at 8,400'. Snow depth here was 95cm (3 feet). We found similar 2-4mm facets making up the bottom 45cm of the snowpack, but we had ECTX 3 times. We were surprised it didn't break or propagate. Despite these test scores, we figured recent snow, wind and a large skier triggered avalanche yesterday were signs to avoid steep slopes, especially if they are wind-loaded.

The sugary, weak facets we found may not yet be showing signs of widespread instability, but combined with more new or wind-drifted snow they could create larger avalanches.

Went into Beehive basin today with a group of people. We dug a pit on a south west aspect just above Beehive meadows at 8384ft to see what was going on in the snow. We got an ECTX for our results.

Went on a tour today with a buddy and traveled through twin falls basin as well as the maid. We skied a NW slope off of Palace Butte and found touchy conditions below the ridge line, but great skiing in the trees. We also skied the bowl of Arden peak. We observed numerous recent wind slabs that released naturally in the past 24 hours on NE and E aspects with some crowns starting to get covered up throughout the day. Judging from afar, I would estimate these crowns to be 6 inches to 1.5 feet deep. 

Saturday afternoon on the way back into town snow was moving in the Spanish peaks. Nice light 

Skied a few laps on Ellis today, E through NE aspects

No slab avalanche activity was observed (minor sluffing on steep, cold slopes)

Got off the skin track in a few places and no whumphing or cracking

Light to moderate ridgetop winds from W and SW

Trees holding snow; no drifting/ blowing snow on Ellis 

Saw A LOT of blowing/ drifting snow toward Hyalite and the Spanish Peaks at elevations above 8000'

Average HS on Ellis summit ridge 100 cm; average ski penetration 35 cm

Dug a quick test pit on a NE aspect at ~7800' (30 deg slope)

Pit results: HS 130 cm; CT 21 BRK at 85 cm; ECTX

No signs of instability; great skiing. Yay!

Thin and variable snow pack in the N Fork (?) Specimen creek drainage. Max depth less than 100cm, min depth bare ground. Active wind loading on exposed ridges, multiple whumphs when skinning over wind loaded, low angle slopes. Decent skiing, albeit thin, on low angle W aspects from 8200’ down. 

We skied on the knob Saturday and Sunday. Dug a pit on the east facing slope just above the steeper roll over. ECTX. No result. Minimal wind loading next to the tree bands. We skied the slope 20+ times (between 4 skiers). 

We took the sled up track around the north side of the knob and below the avy debris from the slide triggered a last week. Only sign of avalanche activity (other then the obvious one) was a small wind slab release on a south facing slope near the top of the pass. Marked on the map below. Photo attached is of the previous slide but the wind slab release would be where the red X is if the photo continued. Looked to be 30ft across, ran for 15-20ft and about 6inches deep. 

My partners and I began a tour today at Hyalite Reservoir with a plan to ski the E and N faces of Mount Blackmore, but with the mindset of keeping expectations low and moving slowly giving time for observations and discussion. 

On our way in, just off the trail in an opening in the forest at 8600' on a NW aspect with an incline of 29 deg we chose to dig a test pit mostly to see if a faceted weak layer might be present on the shady aspects we were planning to ski. The pit showed a fully right side up snowpack with the snow progressively going from F hardness new snow to 1F snow towards the ground and a depth of 110cm. The snow was not wind loaded on the surface at our pit location and our ECT yielded an ECTX and no obvious signs of instability. As we climbed towards Blackmore and subsequently ascended the NE ridge, there were occasional gusts on the ridge that were actively blowing snow. The ascent towards the Blackmore summit only presented small shooting cracks and considerable cohesiveness in the surface snow in an isolated pocket towards the summit. 

We opted to ski both the E and N faces and did not notice any instabilities while skiing the lines themselves.

Skied Mt Blackmore today. Dug a pit at 9550ft on a SE facing, 23deg, slope adjacent to the standard east ridge up-track. HS150cm. No wind effect on the surface. 

Had a CTE and CTM on density changes in the top 40cm, ECTN on the same layers.

Pulling the CT block into the pit, the bottom 100 cm was very well bonded and pulled up dirt from the ground with it.

Skied numerous laps, and did not observe any signs of instability. The skiing was excellent.

Didn't see any windslabs yet on NE facing burn scar. Just like ~2ft of loose fluffy snow. Trees still have snow on them, so wind probably hasn't been that bad.

I got out for a low-angle morning lap with some good folks this morning on Little Ellis and thought I'd send along a couple quick take homes:

1. We found 6 ~ 12" of new snow on our way up (and it skied excellently)

2. We saw no obvious signs of instability (cracking, collapsing, or recent avalanches)

3. We observed no wind during our outing (630 - 830am) and found no wind affected snow

4. Temperatures seemed inverted with slightly warmer temps at ridgetop vs. cool air pooled at the trailhead

5. Dug a quick handpit at the top transition and found a supportable pencil hard crust underneath the new fallen snow with well-developed large-grained facets below that... but the quick hole was in the upper scree/rock garden... so I'd expect it to harbor more basal faceted snow.

I thought this would be interesting to share but while driving around Gallatin gateway today I noticed multiple small wind pockets that released in steep draws in the gateway foothills area. 

I skied on the N/NE facing side of Dudley twice this week, once on 12/13 and again today. On Tuesday we found HS to be no more than 90 cm with the lower 40cm or so being 1-2mm faceting DFs turning to all facets by the lower 20 cm. Seemed similar to the layer that’s being discussed further south but lacking any sort cohesive slab above it (ski pen was mid-pack, boot pen to the ground). 
 

Today there was no more than 15 cm of new snow with minimal wind transport. Surface hoar was widespread even near the ridge line. We experienced one localized collapse on our up track at around 8000’, so seems like this little bit of new load is just starting to tip the scales. 

I got to the top of the south summit around 11am with lots of active wind loading. I traversed the ridge line for a couple hundred feet, kicking away at small cornices to see if I could trigger anything. Got two small 6-8” deep soft slabs to propagate 10’ wide and a couple hundred vertical but nothing major. The ridge line is too rocky to traverse right now so I dropped onto the face, still staying near the ridge line. A hundred feet or so further across my traverse, it got deep. Cross loading from the north grew a drift that was thigh deep at least. Very cautiously I tried to regain some elevation to get above anything that might pop off. A few steps up the drift, I heard a whumph and it started to slide. I would estimate 2-4’ deep, 150’ wide. It immediately caught my skis and started taking me down. I pointed them down hill and started to pick up speed hoping I could cut out of it. It started getting very deep and turbulent so after 200-300’ I pulled my airbag, while still trying to stay on my feet. Thankfully, I was able to stay up and cut out of the slide roughly 500’ below the summit. It ran full length into the bottom of Argentina bowl and south gut with a massive powder cloud. Way too close of a call. I skied down the avalanche path then back to the resort with my airbag deployed in case of any other slides coming down. Made it back to the resort touched base with ski patrol to alert them of the slide, give them information on my condition and the possibility of other skiers out there (no possibility, I was first person up and didn’t see anyone ascending from the gate when I crossed to south summit) and headed home.
 

Dug in 1st and 2nd Yellowmules. Found 3-4 ft of total snow with 1.5 ft of 2mm facets at the ground in both pits. Fist-plus hardness. ECTP23 & ECTP24. The structure looks similar to what we've been seeing in the S.Madison and Lionhead area. This is the farther north we've found the thick layer of facets and makes us suspicious it might be in other areas north of Big Sky.

5-6” new snow. New snow was somewhat drifted, but not intensely.

Saw a small (R1D1) wind slab avalanche along the 2nd Yellowmule Ridgeline. ~20 ft wide, 1 ft deep, and ran 100 vertical ft. Looked to be wind drifted snow that broke yesterday.