Snow Observations List

We rode through Second Yellow Mule, and then we headed back towards Cedar Creek. There was 2-4" of new snow throughout the area. Next, we rode to Bear Creek and dug a pit. We dug on an east facing aspect, and there was ~4 feet of snow (HS = 130 cm). We had an ECTX. Despite the crust and some warmer temps before today, the snowpack is still dry throughout, and there are still facets in the bottom half of the snowpack. During our ride we were looking for recent avalanche activity, and we only saw a couple of small point releases. We are still concerned about large, unsurvivable avalanches breaking on the weak layers deeper in the snowpack.

Skied on west and east sides of Woody Ridge.  Observed a few small soft wind slab avalanches involving only new snow around the submarine. Dug a pit about a meter deep on west aspect about 9,700 feet.  HS was 290cm. No result on extended column test. Fist to 265, 4F to 245, 1f to 200 where there is a crust layer, back to 1f below that.

Toured into the hellroaring creek 3/15-3/19. Snowing and blowing hard on 3/15 till approx 1500 hrs when wind veered to the north and skies cleared for the rest of the trip with generally cold temps and light winds. Solar aspects heating up in the day with extensive sun crusting on steeper slopes facing the south half of the compass. Observed aftermath of extensive avy cycle(s) one of which prior party reported occurred approx 3/10-11 at higher elevations on Nemesis (above 8000 ft.). And another on lower elevation steep slopes above creek at approx 7500 ft that may have ran during the storm on 3/14 as less snow covered that debris than the higher elev runouts. Everything observed were on westerly aspects and deep slab avalanches breaking approx 90-120 cm down. We did not investigate the weak layer. Suspect it to be the crust facet combo observed by a previous party in early March. Heavy wet snow possibly mixed with rain on 3/14-15 likely tipped the scales for these lower elevation slopes below 7500. No signs of instability of the new storm/wind slab during the five day trip, however we did get a few large collapses but these were isolated to heavily wind loaded areas in more exposed terrain. No other natural or human triggered avalanches observed during the trip. Many machiners were out testing steep slopes after the storm and we saw no signs of any human triggered avalanches. We did not measure height of snow but judging by the buried hut and the non-motorized boundary signs barely poking out of the snow, thinking about 10 feet deep at 8000 ft.

We skied into Frazier Basin, and down into Ainger Lake area. We dug our first snow pit on a north-facing slope below Thing One and Thing Two. The Snowpack was deep, and the upper meter consisted of layers of wind slabs on top of wind slabs (Ectx). We dug again on a northeast-facing slope below Frazier basin. Similarly, we found a deep snowpack with no notable weak layers in the upper 4 feet. We dug a third pit on a southeast-facing slope as we skinned out. The snowpack was much thinner (140cm), and we found weak depth hoar buried 3 1/2 to 4 feet deep with an unstable test result (ectp21). The instability was related to the snow depth rather than the aspect. Given that there was a large natural avalanche a few basins to the south a week ago, we remain concerned about avalanches breaking deep in the snowpack.

As we returned to Frazier Basin from below, we immediately saw five natural avalanches on the southeast-facing wall of the basin. These had occurred while we were skiing the terrain below. They entrained only the 1 to 2 inches of snow that had fallen during the day. However, they were notable in that they ran 500 to 700 vertical feet. They were likely initiated by warming from the proximal cliff faces. They indicate that the new snow may not bond well to the old snow surface. A crust formed by the recent warm temperatures and sunny skies is the subsurface that snow is falling on. This will become a more significant concern as more snow falls this week.
 

We rode into the Taylor Fork area on a beautiful, sunny day. We saw three large avalanches that likely broke approximately one week ago in Sunlight Basin, Sage Basin, and at the head of Sage Creek. Sage Basin and Sunlight Basin were cornice-triggered hard slabs that broke 2-4 feet deep on wind-loaded slopes. The avalanche in Sage Basin broke several mature trees.

The slope that avalanched at the head of Sage Creek was a heavily wind-loaded 35-40 degree slope. It failed without a cornice trigger (as no overhanging cornices were above). We investigated this slide in greater depth. It failed on a layer of faceted snow 2-4' deep. In our stability test, we got an ECTP22 on the failure layer. Riders and skiers are less likely to trigger these large avalanches after four days without snow, but we don't trust these slopes. Every time it snows a little bit, we see large avalanches. They remain possible to trigger now. Choosing conservative terrain is the best management strategy - simple slopes with minimal wind-loading and fewer consequences or slopes less than 30 degrees in steepness. With more snow in the forecast, the danger will likely rise again this week. 

Yesterday we toured up into Emigrant gulch. At around 2pm we observed a small point release on the East face of Emigrant, either a small cornice break or wet loose, that ran for about 200ft before stepping down to a deep slab that appeared to be about 3ft deep and 100ft across. 

Attached are a few photos of old deep slab avalanches north of town. 

The first photo is a south face north of round lake above 10,000’. The crown was mostly filled in but the deepest exposed part was 2-3’ deep. 

The second is the south face of scotch bonnet. Hard to tell the depth of the crown but it’s very visible from the lulu road, so probably pretty deep. 

...Saw lots of recent small soft avalanches that broke pretty (8-12”) shallow in the new snow for last week, both in wind drifted areas and non wind loaded slopes. 

Dug two pits on Texas Meadow north of Bridger Bowl. Generally good stability. Main concern is recent snow which appeared well bonded in pits. Deeper weak layers were stubborn to non-reactive, but a few deeper layers exist enough to create a deep slab concern if there is more loading, or when things start to melt...

Recent avalanche activity along the range (from Bridger Peak to The Throne) was confined to loose snow avalanches involving the most recent storm snow. A few natural, and many skier triggered which were large and probably occurred a day or two ago after 8-11" of heavy snow fell. There was minimal recent wet snow activity. Slopes that face the sun had a 3 cm crust which started to get damp this afternoon, but cooled off before it became weak enough to create any wet snow hazard.

Shady slopes stayed dry, and there was evidence of near surface faceting on shady slopes, and a thin dry layer of facets formed above the crust on slopes facing the sun.

Slab avalanche on NE facing slope at 7,500 feet - slid to the ground.   

Myself and two partners were skiing in the crazies 3/17-3/18. Dug 2 pits and got similar results, ectn15 18cm down and n28 30cm down with depths of 300-400cm and no deeper pwls on N/NE aspects at 8300ft and 9600ft. No recent avalanche activity other than a few small 6in storm/wind slabs on southern aspects. Snowpack was very right side up everywhere we toured and had skied 3 different NW to E faces. On 3/18 we headed to ski a NE facing couloir at 10000ft, skinned/booted the first ~300ft and found similar snow to everywhere else. About halfway up hit a rocky section with some depth hoar, I noted plate crystals up to 1cm wide at ground. Should’ve turned around there but thought maybe it was just a short rocky section. I had also just measured the slope angle at 52 degrees which gave me false confidence there would be no developed slab. Wallowed through weaker snow for another ~50ft then finally decided to turn around due to the difficult boot packing, hitting our 3pm turn around time, and the weak snow pack. As I booted to the middle of the line to find better snow the slab broke off 10-20ft above me wall to wall. I was the only one caught and was carried 500ft of vertical. Didn’t get buried and no lost gear so extremely lucky all around. The avalanche was estimated D2/R4 with a 18-30in crown and 30ft wide.

D3 slab avalanche on SE corner of Giant Castle Mountain north of Pahaska, WY appears to have been triggered by a skier between 3/16/2023 and 3/18/2023.

Large avalanche crown across the east facing saddle off the north side of Electric Peak. Roughy around 10,500 ft, around 800 feet across the crown, looked to have broke around 1-2 feet deep and would guess it happened in the last few days. Lots of active wind loading happening. 

Watched two riders on the north side of Henderson / Daisy pass high marking. One triggered an large avalanche and got stuck at the crown. Crown was taller than him. Guessing 8-10’ deep and 200+ yards wide. His friend had his back turned to the slide and didn’t see it happen. We were across around the sheep mtn/ Scotch Bonnet area and watched the whole thing happen. We boogied over there as fast as possible to help. 

Numerous slides observed on Saturday 3/18 on the flanks of Emigrant Peak during a tour up its east bowls. The largest ones seemed to be on SE aspects. 

A few recent slides were visible today on south, east and west aspect around goose lake zone. Looked like mostly wind slabs in the new snow.  Pit on East aspect was deeper than three meter probe.  Showed relatively right side up pack in the first meter. ECTN 23 about 20 CM down. No other signs of instability observed. 

Riding around Lionhead and into the back bowls revealed an extensive avalanche cycle that occurred with the Avalanche Warning 2 days ago. Some slides were hard to see since they were buried in snow while others were more fresh. Crown lines near the ridges, debris piles at the bottom of slopes, and debris pushed high onto trees were evidence of the recent activity. Many slopes avalanched; more than we've ever seen in this area.

We dug in 1 crown and measured 11" of SWE above the weak layer (1mm facets) that avalanched. Every weak layer has a breaking point, and this layer needed about 11 feet of snowfall to get it to avalanche.

Big scary avalanche on a wind loaded slope on mount Bole.

Side by side D2 natural slab avalanches at on SE edge of Giant Castle Mountain north of Pahaska, WY (occurred on 3/16/2023).

From the FAA road up Sawtelle Peak outside Island Park we were able to see many crown lines and debris piles from the last 2 days of Avalanche Warnings. Most avalanches involved new snow, but there was 1 deep avalanche on Mt. Jefferson's east face that was large (D3). The FAA did avalanche control and an avalauncher round triggered a small, but deep slide (2-5' deep) and a larger explosive on another slope yielded no results. We saw 8 backcountry avalanches from the road. These were east and north facing, the only aspects available for viewing.

The snowfall totaled 3' and it will take a few days for the snowpack to become more stable. In the meantime, be patient and stay off of steep slopes.

Saw this natural D2 soft slab off the east aspect of Miller Ridge. The crown looks shallow, so I’m guessing it ran at the storm interface.

No other avalanches or signs of instability observed. Winds were light out of the NW and the HN of the settled snow was about 10cm.