Snow Observations List

After a long day of riding 2 to 3 thousand feet higher in good snow I was getting close to the truck after 10 or so miles on a mostly hard pack trail I decided to climb this hill in a split second decision. My sled was overheating and my plan was to cool it down. As I ascended the hill I hit a pencil hard wind slab about a third of the way up, I knew instantly that I was in trouble as this slope ended up being much steeper than I had initially thought. I made a decision in the moment to continue up the slope as it was not many vertical feet in elevation. My thoughts were that I had lots of speed and momentum built up and that that would carry me up I also thought that if I tried to make an aggressive turn it would put more stress on the snow pack and I also figured the closer to the top of the slab I was when it fractured the better off I would be. I made it about 100 feet from the top of the hill when it first fractured, I was about 20 feet from the fracture and there was a point slightly to my right that was the closest point of the fracture to me. I turned slightly right heading to the closest point of snow above the fracture line. As I turned the slope started sliding. The top of the of the slide rolled over like a large wave and a block hit me in the ribs luckily not nocking me off my sled. I maintained full throttle and kept my momentum traverseing through the rolling blocks. My only thought was to try to stay on top of my machine and keep forward momentum. In the last few moments of the slide I could feel I was loosing control of my machine because it was starting to get sucked into the avalanche. When the slide stopped I was in snow to my knee on my uphill side. I want to end this with a warning of complacency. I had been in big terrain all day and didn't analyze the slope like I should have a simple glance for a moment and I would have recognized the dangers of the wind slab. I got complacent and it almost got me injured or killed. Just because a slope is small doesn't mean it isn't dangerous.

**Reporting this from a friend of a friend. Not my photo, nor was I involved.**
 

one skier got caught above large bottom cliff, carried all the way down over cliff to the apron. Said skier walked away completely unharmed. Not buried. 
 

north face of that bowl, near cornrows. 

Additional info from BSSP: 

"There was a large, deep slab avalanche snowboard triggered in Lone Lake Cirque this afternoon. The
slide ripped in a secondary start zone below ridgetop, and ran far into the flats, and may have run a

bit uphill, where it encountered the rock glacier moraine in the runout. It looks to be a R4, D2.5."

From IG:

Think this was a recent natural up buck I saw today. Didn’t get close enough to see but looked like it was a big crown… down low 8900ish SE

Uneventful day. Rode through all three yellowmules, McAtee Basin, and the heads of Muddy and Bear Creeks. Saw no recent avalanches or other signs of instability. Dug two snowpits on E and N aspects at ~9400 ft. About 12" of snow from last weekend with 1.3" snow water equivalent. ECTN14&16 under the new snow. No other results.

Snowing lightly with overcast skies and calm winds. We'll be paying attention as it starts snowing tomorrow, especially if the wind picks up as forecasted. 

Via phone message:

A large natural avalanche occurred on the north summit of Bridger Peak yesterday (Monday, 27 March). The crown line was complex.

We rode into the Throne from battle ridge and skinned up the east face. We saw three new snow avalanches (previously reported) on the SE and E faces of the Throne where we parked the sleds. Surface crusts are quite variable depending on slope angle, aspect, and shading from trees. The crust was generally present and breakable on the SE and E aspects we traveled on. We dug a quick pit on at the base of the E face. ECTP16 on 1 mm facets underneath last weekends snow. We measured  50 cm (20") of new snow with 2" snow water equilavent.  Dug again in the crown of one of the slides. The new snow had consolidated a bit because of a more southerly aspect (~16" deep), but there was also 2" of SWE in the crown. Slide broke on small facets above a firm crust. The slides all appear to have run mid storm or just as it was ending. One of the slides was clearly skier triggered, the others are unknown.

The presence of facets under the new snow means that it'll take longer for that new snow to stabilize. 

On my walk up to divide today 3/28 I noticed a few small storm slabs that broke on the west side of the main fork of hyalite off the summer trail.  This area had similar storm slabs that broke back in mid February during a large storm 

up in the alpine there were no avalanches to report 

On a sunset tour we headed up to grab some low hanging fruit in the W Bridgers. We were shocked to find such a deep snowpack in the plains. Skiing a meadow off the valley floor from the North Cottonwood Canyon TH, we dug a pit at an elevation of approx. 5,800ft on a west aspect. The snowpack was 85cm deep, with this weekends new snowfall making up the top 45cm, the sun had affected the top 5cm creating a thin warmer layer and then surface crust as temperatures dropped. The bottom 40cm was a melted down, 4F hardness layer of weaker snow to the ground. At the moment the new snow appeared to be bonding well to the previous snowpack but it was very visible that this bottom layer was trending towards faceting and weakness. Our test result was ECTN 14. There was no breakage into the weak snow below the new snow. We skied a beautiful 25-30 degree pitch into the setting sun.

We observed evidence a couple of recent slab avalanches at the throne

From IG: Battle ridge today/yesterday the 27th. Noticed this and a few other smaller solar releases as well as a couple storm slabs from during the cycle. Sun crust formed rapidly and there was a lot of wind loading in the afternoon

We rode through to the Goose Lake wilderness area boundary and skied from there to look at the snowpack in higher elevation, alpine terrain. Like the day before, we managed our exposure to avalanche terrain be keeping ourselves off and out from under large slide paths because of our concern for the possibility of deep slab avalanches. 

We dug two snowpits on the tour and found a layer of surface hoar buried 20 CM deep (on the far end of Goose Lake at ~10,000' elevation on an east and northeast-facing slope). It did not propagate in any of the tests we performed, but it is certainly something to watch for. We did not see it in our snowpits yesterday, it will take more time and more snowpits to pin down the extent of this new weak layer and whether it will become a widespread problem. 

Our two primary concerns for today were wind slabs, we observed several recent wind-slab avalanches on Mount Fox and Henderson Mountain, and deep-slabs like the one that caught a pair of riders on Thursday on the SW side of Henderson. 

Two large, widely propagation fractures visible through a hole in the cloud cover Monday A.M. from Bridger Canyon Dr. Upper slab failure evidently stepped down to a deeper layer estimated 400' below upper crown. Both crowns appeared to be similar depth. Also visible were debris toes further to the North that had run mostly full path. Looked like it was already covered up yesterday (tues).

Toured in Emigrant Gulch on 03/27/23. The area recieved much less snow during this storm compared to nearby ranges or Northern Absarokas. ~15-20cm of new snow @7000ft, ~20-25cm @9000ft. Dug at quick snowpit on SW aspect of Chico Gully @7000ft. Snow pit was 180cm deep. ECT showed no reactive layers or propagation. However, primary concerns were a sun crust 60cm down in the snowpack and weak surgery snow near the ground. Skinning up the gully we experienced multiple whoomphs in shallower areas near 8000-9000ft and turned around. Skied up to the base of Emigrant Peak SE Gully and experienced several whoomphs at 9000ft likely on the sun crust found in our snowpit. Surface snow was fully saturated at that point. Turned around and enjoyed mellow powder skiing out.

We rode up to Daisy Pass, then back to Marty's. We skied up to the starting zone and found the thinner (100-150 cm deep) and weaker snowpack typical for this area. We found weak depth hoar near the ground and layers of surgery facets in the middle of the snowpack. This path slide 1.5 weeks ago, likely triggered by a rider. Four days ago a slide caught two riders and seriously injured one on the same aspect of West Henderson a mile from where we were. The snowpack structure was similar. The scary thing is Cooke right now is that avalanches are not happening on every slope or every day, but when they have occurred recently, they've been big.

We recommend either choosing terrain very unlikely to slide because it is less than 30 degrees and not underneath steep slopes, or choosing terrain that minimizes the consequences of getting caught - small slopes that don't have terrain traps like gullies, trees, rocks, or cliffs. And always, travel one at a time on the slopes while watching your partners from a safe spot.

We saw a smaller natural avalanche on Ray's while driving into town, north-facing slope, 2-3' deep, not very wide. This was the only recent avalanche we saw today, but the visibility was poor and we didn't cover much ground. 

Saw a couple small natural slides breaking in the new snow. The one on the small slope beside the road actually appeared to have broken when a snow bike crossed the top just off the side of the road. The other was natural and occurred in the afternoon sometime 

Near Big Sky today we found 8-14" of right side up storm snow from 7500' to 9400' on a south southeast aspect.  We observed very minimal and isolated cracking on the occasional wind pillow, but by and large the snow was non-reactive, unconsolidated, and very well bonded to the stout crust below.  

Winds were light and variable and it snowed lightly all day, accumulating about 3" by the late afternoon.

Came across debris of a recent skier-triggered slide near the top of Little Ellis in a small, protected, eastern facing gully around 7,500'. Crown was ~3.5-1.5' deep, ~35' wide and it ran ~150'. Ski tracks were observed near the top of the crown and next to a small hole near the surface ~70' from the crown where it looks like someone self extracted. No signal was found with a beacon search and my group felt that the one track from the hole must have been from the same skier as the track near the crown. 

There was around 2-3' of heavy new snow at that location.

Toured into Moser Creek on 3/25 to find some pow turns. Measured 85cm ~34” of new snow and saw many shooting cracks on a density change in the new snow but surprisingly no propagating pit test results. It seemed that the snow was so new and so low density that it wasn’t making a cohesive slab. There was a stark new to old snow interface.

From GVSA groomer via text on 3/24/23: "Small slide in Buck just below 5 mile on the road cut. Likely natural. E Face about 42 degrees, 6-8" new up on top with 10 mph wind out of the SE. Cuttently snowing at .5"/hour (9pm)."