Snow Observations List

From Big Sky Ski Patrol: "Temps remained a little cooler than yesterday and generally topped out in the mid 40’s F. That didn’t stop the free water from moving
and continuing to destabilize the snowpack, primarily on solar aspects below 10,000’. Near full depth to full depth wet loose avalanches continued to naturally release in what was left of the A-Z’s as well as LRT which had not seen any activity yesterday."

We rode up to Lulu pass, around the back of Fisher Mtn, behind Crown Butte and out Miller Creek south of Crown Butte/Daisy Pass. The upper snowpack was wet, but supportable. We dug down about 3 feet in a meadow in Miller Creek. HS 255cm. The snowpack was wet in the top 20 cm. -1.5degree C down 20cm and -3C down 60 cm. Still dry 40 cm below surface.

Wind was strong out of the southwest. Skies became mostly cloudy around midday, but seemed to clear slightly in the afternoon. Temperatures in the high 30s to mid-40sF.

There were maybe 6-10 D1.5-D2 wet loose slides scattered around the area that we could see, similar to attached picture of Crown Butte (We could see Miller Mtn. east and north, Scotch Bonnet, Henderson, Crown Butte, Abundance, Wolverine). At lower elevations where the snowpack is shallower, closer to silver gate and the northeast corner of the park, there were some deeper wet loose slides (D2) and a couple small wet slabs (photo). I would estimate most of these happened yesterday (4/10). Today, a D1.5 wet slide buried one lane of road in YNP on a steep, treed ENE facing slope at 6900'.

From IG: “Couple shots from today In the cooke area.”

Drove Bridger Canyon to Seitz road around 5pm on 4/10. Saw 4-5 D2 wet loose, plus many D1 wet loose. No huge slides or widespread large wet activity, yet.

From email: "This afternoon en route back to Livingston from Idaho, lots of slide activity at all elevations…

The first picture is the cornice collapse. One block in the debris pile was probably the size of my airplane - a giant ass snowball. 

The next few photos are wet slab a mile north along the same ridge, location: approximately 1-2 miles SW of the coordinate photo (it took me a minute to get cords up). Elevation of both approximately 9,800-10,000. 

Too many point releases to count in every range I’ve crossed today…"

While descending from a trail “run” (definitely more of a post hole) up towards Baldy, I saw a medium-sized wet slide on the eastern side of the ridge underneath some large rocks. The slide was roughly 15-20’ across at the portion I could see and traveled several hundred feet down the mountain. I could hear trees snapping (sadly in the video I don’t think you can, as my breathing is way too loud) and watched the avalanche move for almost a minute. I was very thankful for my careful route finding and avoidance of steep slopes! 

~ (45.7311237, -110.9639991)

Big Unit of a avalanche, photo taken from the Seitz road.

Today we observed wet loose avalanche activity on the southerly aspects in the mountains around Pioneer mountain. We also observed one dry slab avalanche on a NE aspect of Sphinx mountain at approximately 9,000’. 

We toured in Hyalite today. By 10:30 in the morning we saw wet, natural avalanches coming down east facing cliffs. We also saw several pinwheels from yesterday. By noon we were at 9,900' on a SE facing aspect, and the snow surface was wet at this altitude. Once we were down at 9,000' the top 8" of snow was wet, and it was beginning to move as a slab on small rollovers.

We skied three runs south of Quake Lake, up to 9400 ft. Most snow was crusty until it warmed up, but we found some powder in the shade and on north and east aspects, especially up high.  Dug a pit at 8400 ft, N aspect, 32-degree slope.  Result was ECTN-20 at 25 cm, and ECTN-22 at 35 cm.  Sheared fairly cleanly.  We were halfway up the avalanche chute at that point, so skied down with no incidents and skied two other tree runs.

We toured into Emigrants southeast bowl on Saturday. We found thin and reactive wind slabs on north facing slopes. Our ECT on a north face gave us stable results below the wind slab layer. It was the second day in a row of high temperatures and full sun but there was very little wet slide activity in this zone. We observed multiple old crowns in the surrounding mountains that looked to be a few feet thick. They were possibly breaking on a crust layer we found about 2 feet deep in our pit. 

Documenting local avalanche cycles, attached is a photo of an avalanche on the south face of Mt. Abundance taken yesterday, that likely happened last Sunday (?) when we got 1" of SWE overnight.  Lots of debris chunks the size of refrigerators.  Crown mostly covered by wind blown snow.

We toured out to republic pass. Saw mutliple small natural wind slab releases. We dug a pit on Republic Pass around 9800 ft on a north facing slope with lots of wind, got an ECTP 26 @ 30cm down from the snow surface on a very thin layer of facets. We only dug a ~5ft deep pit but found very stiff and solid snow throughout the snow pit (1 finger to pencil stiffness). Very little fresh snow was on the surface due to the wind ripping through the pass. It snowed for the whole first half of the day, lots of wind but only about 1cm of accumulation.

Lots of naturals and maybe a rider triggered avalanche seen today. Steep solar aspects had lots of wet loose activity and small cornice/pillow fall. 

Went for a ski on Jumbo Mountain via the Lava lake parking lot....

The big surprises for the day were 3 separate deep slab avalanches since the most recent loading event (likely 4/3). Photos are attached. The first that we sighted was on the N/NE face of Jumbo. It appears to be cornice fall triggering a windslab that stepped down, photo attached. 

HS-N-R2-D2-O @ around 10000ft on the N/NE face of Jumbo.

the next that we sighted was a large deep slab on the E face of the ridge just north of the true summit of Jumbo. 
 

HS-N-R2-D2.5-O @ around 10,000ft. 
 

The real show stopper was on the E face of Jumbo.

HS-N-R4-D3.5-O/G. Approximate crown width of 1000ft and average depth of 6-8ft. Total run of around 2000ft. A few photos attached. 
 

other slides of note, a few D1-1.5 WL slides low in the basin SW facing. Also, an older deep slab on N facing terrain just south of Hell Roaring Lake, D2-D2.5. 

 

I went through the area of Three Rivers Peak yesterday, and there had been a pretty nice cycle of large slides recently. One on the east face of Three Rivers broke 6-800’ wide 2-10’+ deep, and ran full track. It only had a couple inches of snow on it, so I think it ran sometime during the recent warm days. Some of the walls along the slide were over 20’ high, and I imagine the debris pile might make it through the summer. 
I also observed a couple older slides on E\NE aspects that were older, but not a whole lot smaller. 

Small wind slab triggered by snowmobile. Slope was assessed by group as wind blown before climb.  No one was caught. East facing slope, Storm castle Ridge.   
Photo one shows trigger point where the Snowmobiler carved hard and set off the slab deeper in the snowpack
 

We rode through Carrot and Sage Basin and up to the weather station above Sunlight Basin. We dug a pit on a SE facing aspect to see if the snowpack was transitioning from dry to wet. At 9,200' the air temperature was 18 F and the snowpack was dry throughout. Despite the cool temperature the snow surface was close to becoming wet (31 F). This was a good reminder that the sun angle has a significant impact on the snow surface this time of the year, which causes rapidly changing conditions. Additionally, we had an ECTP 13 on a layer of near surface facets 1.5' below the surface sitting on top of a melt freeze crust. This weak layer and the one near the bottom of the snowpack remain a concern.

South of Saddle Peak, ~8500', ENE aspect, 2-3' crown depth estimated and likely cornice-triggered. N-facing snow remained dry until the latter afternoon when a high sun angle cooked everything but the truest due north. Avalanche appeared to be all new snow likely on a PWL buried near the end of March. Winds moving snow up high, but everything appeared locked on.