Snow Observations List

Today I was skiing a south facing slope between 8500-9500 ft near Mt Henderson. I observed at least ten large collapses, some of which sent cracks 30 feet long. This slope had a shallow snowpack relative to the rest of the area. 

We drove and then rode up Little Bear this morning on the 3138 road (also snowmobile route #900).  Once 3138 splits off from 980 there was mostly enough snow for riding on the road without issues but little else.  Snow depth varied from 4-6 inches, down to 2-3 inches in sun and wind exposed areas, to as much as 18 inches or so higher up (8400').  We also saw some spectacular surface hoar- probably 1-2" tall in places with extremely sugary snow underneath; often so sugary we weren't leaving well defined tracks behind our sleds.  As with everywhere else, we heard some collapses while off of our machines.  

From email: 12/13: "Many slopes had half-inch to inch-sized surface hoar crystals on the surface, some of the largest I've ever seen! 

Wind was light out of the north on the ridgeline. We noticed 2 natural avalanches on the east-facing slopes below Bald Peak. I lost count, but we experienced well over 30+ collapses while walking on the ridgeline. Many of these collapses were very large and we were able to watch the slopes 'sink' by upwards of an inch which made our hair stand on end.

We dug a pit near the saddle below Lionhead Peak at 9300' on an east-facing slope (HS ~85cm). We performed an ECT and our results indicated poor stability (ECTP 14 @ 50cm)." 

From email: "Over the last couple days, I’ve been seeing very large surface hoar formations on most of the snowpack from ~7000 ft+. They continue to grow day to day, I’ve measured crystals over 5mm tall. Hopefully the warm temperatures over the next week will melt these before our next storm cycle, but only time will tell."

We rode into Tepee Basin to look at an avalanche that was triggered by riders on Saturday (12/9) from the flats below the slope. On the way in we saw widespread and large surface hoar on the snow surface. We dug a snowpit next to the avalanche and we saw ECTN results (ECTN 13) on weak-faceted snow under early December snow. This was the same layer that the avalanche failed on. Recent avalanche activity and poor structure were more than enough to keep us from riding steep slopes. 

Aspect was NNE 070 deg. 8100 ft.

85 cm snow depth

First 20 cm from the ground up was large facet, rotting snow.

Remaining 60 cm was consolidated.

No collapsing or shooting cracks noted. 

No natural slides seen in the area.

Spoke with another party that was skiing S of The Throne. They heard large collapses while skinning over flat terrain. 

I walked up from Halfmoon this morning to see what is happening with the snowpack in the Crazies. I only went up to about 7000ft, temps were in the mid 20s and wind was very light out of the west. Not surprisingly, I found very minimal snow coverage, with the deepest snow I found around 3 in. South facing aspects were almost completely bare, and much above tree line appeared totally scoured. Where there was snow on the ground, on average 1-3 inches, there was a thick crust with large surface hoar crystals on top and very light density snow below. Didn't look great, I left my skis at the car!

From email: "Skinned up to about 8600ft in Mill Creek area near Arrastra drainage. Frequent collapses heard/felt once above about 8k, where snow totals seemed to average 12-24 inches on E to N aspects, more up higher. Sparse/discontinuous snowpack below 8k. Lots of 1cm surface hoar in protected areas.

Saw a couple recent (<48 hours old) large crowns up higher in the E facing bowls around 9800ft, one of which appeared to be triggered by a cornice fall (not pictured).  Lots of ridge top wind transport a few days ago in this area, none seen this morning"

Got a view of the bowls behind maid of the mist and above twin falls today. Multiple natural wind slabs, up to size 2, on E and NE aspects, roughly 9500 ft. SS-N-R2D2-I.  My guess is they are roughly 48 hrs old.

Spent the day up near ski hill with West Yellowstone Avalanche Fundamentals course. 

Our group observed a large collapse below ski hill.

We dug various pits @ 8000' below ski hill and found HS 85-55cm on NW-NE aspects.

The snowpack structure there had weak snow at the ground capped by a stout ice crust with faceted snow over the crust beneath the recent snow.

We recorded ECTP4, ECTP11, ECT20 & a few more propagating results on facets above the crust. 

There was widespread intact surface hoar. 

Skinned up the closed ski area to the Fingers Meadow above the Pierres Knob chairlift. Got a substantial collapse (whumpf) while skinning and stopped to dig a pit at that location. E aspect, 8100 ft. Snowpack consisted of 6-8" of old, weak, faceted snow at the ground capped by ~18" of snow that has fallen over the last week. 

ECT broke on the old snow while isolating the column. Twice (ECTPV x 2). Clear signs of instability kept us out of avalanche terrain. 

Lots of collapsing today near Miller Ridge (S, SE facing slopes), just 50' from the road. This continued in more sheltered areas as well. Dug on a NE facing slope at 9300', HS: 80 ECTP12 @ 40 cm. 

NE aspect 7600 ft.

Hand pit - 40 cm deep

First 15cm of the snowpack from the ground up, was rotten, un-compacted snow, with a thin hard crust.

Top 25 cm was compacted snow, density 4F. 

S Brackett Cr road has a few inches over most of it. Snowpack is still too shallow to allow for much skiing.

I went with a party of 4 to check out the ice climb Tequila Tour - what we believe to be "Willis Route" in the guidebook.  This is the next significant drainage south of Horsetail Falls on the west side of the east fork valley.

Around the base of the climb (45.43740, -110.91324), we found on an unshaded south facing aspect a snowpack of 30-40cm.  Icy crust layer for the bottom 8-10cm with 4F harness and then very fluffy new snow on top.

Lower down near the creek, the snowpack is thinner - much of the recent snow and wind transported snow is up in the trees.

Today, there was a quick dump of new snow, lasting about 30 minutes.  The sun came out briefly afterwards.

Our party got to the bottom of P1 and turned around.  While we knew the gully between pitches is relatively low angle, we were a bit uncertain about the size and positioning of hanging snowfields above and knew that today's forecast was considerable.  Something to revisit later.

Toured up toward Mt. Blackmore today with the goal of skiing the mellow SE facing meadow and familiarizing myself with the current unstable snowpack. While stopping for lunch I dug a quick pit out of curiosity and performed a CT at 8757’ on a NW aspect with HS 85cm. Results were CT11 down 17 cm within the new snow on a hardness change and a CT13 down 35 cm on old facets. Moving farther up in the basin we noticed the pictured recent D2 avalanche on the E aspect of Blackmore. As we skinned up the SE meadow, we experienced three audible whumpfs. Otherwise great skiing was found today albeit a bit thin!

Dave Zinn saw two avalanches, had a large collapse and an ECTP3 in his stability test.

Like the rest of the advisory area, the snowpack in the Taylor Fork is unstable and consists of a weak foundation capped by a slab of snow. Considerable danger, recent avalanches and collapsing were enough to keep us off steep slopes. Without new snow this week, you will observe fewer obvious signs of instability, but the weak structure will persist, and any steeper terrain should be approached cautiously.

From email: "I dug a pit in the normal location to check the snow pack conditions and here’s what I found.
Aspect: East
Slope Angle: 19
Elevation: 8100ft
Total pit depth 70cm
Winds: light 5mph with gusts up to approximately 15mph. I wasn’t on the very top of the ridge so I was a little protected.
ECTP 22 The failure was right at the old snow and new snow line 27cm up from the ground.

The snow coverage of the parking lot, trail up and off trail areas wasn’t great, but I’ve seen worse."

Collapsable snow on SE and NW aspects of the parks above the meadow.

ECTPV, PST-end

NNW, 7489'

Yesterday 12/10/2023 at 0900, my climbing partner and I observed a clear crown line extend that extended throughout much of the east/ north east aspect of the bowl on Elephant Mountain. 

My partner and I were both surprised by the depth of the crown. The eastern most point of the crown (photo left) was the deepest.