24-25

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.

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.

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

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! 

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. 

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.