Snow Observations List

We skied near Lulu Pass and dug a pit on a northeast facing slope at 9,500'. There was 6-8" of low density new snow on top of a thick layer of surface hoar (10-16mm, photos attached). Snow depth was 90cm. There was a layer of small facets directly below the surface hoar, and below that the snowpack mostly had rounded grains and showed little signs of weakness. We had an ECTN12 on the surface hoar layer. While skiing I saw some 5 foot long cracks across the snow surface on a wind-affected convexity.

I'm not sure how widespread the buried surface hoar is, but this will be our primary interface of concern when we get more snow. We did not find surface hoar on south and west facing terrain in this area, but there was a crust with small facets below it buried 6" deep. Right now there is not quite enough recent new snow to create widespread instability. I do suspect a slab of drifted snow or a wind stiffened slab could propagate easily, especially if it lies on buried surface hoar.

Light snow fell most of the day with maybe an inch of accumulation all day. Wind was light and temps were single digits to low teens. Some moderate gusts in the afternoon, and winds increasing in town this evening. 

Just an initial look at low elevation snow around some of the ice climbs.

8" of new snow at the Grotto Falls TH. 
 

I couldn't find any surface hoar that was buried by last night's snow, but I'm sure it's out there. Doesn't really matter because there's plenty of weak, faceted snow that was the previous snow surface.

The new snow is all fluff and not a concern at lower elevations in Hyalite. Perhaps it could be enough of a load and enough of a cohesive slab at higher elevations where more snow fell. 

For now, things seem mostly stable, but that will change quickly with any amount of wind. 

Noticed this natural avalanche on 12/8. East facing slope, ~9500 feet, Hayden Creek above Ripcurl area 

We skied around Scotch Bonnet and Sheep Mtn., north of Cooke City today.

No collapsing nor cracking, nor any avalanche activity observed.

Snow profile attached from a SE aspect at 10,000' on Scotch Bonnet.  HS65, ECTP22 @25.

Surface hoar (4-8mm), observed on most slopes, except on steep solar slopes and especially windy locations.

Lots of surface hoar. Those crystals are often destroyed before being buried, but surface hoar is a good sign of weather conditions that are good for near surface faceting.

The upper few inches of snow is a mix of broken snowflakes that are starting to facet a little bit. Not too terrible yet.

Deeper layers of old November snow closer to the ground are faceted and breaking in stability tests. To get an avalanche breaking on those facets, I think you need an old wind slab on top. Even then, I think the sensitivity has dropped a lot. 

We did see one recent wet loose avalanche that started near some exposed rocks in a place that typically gets wet. I did NOT see any wet loose slides in East and Southeast-facing gullies on Barronette peak. However, I'd be nervous ice climbing in these gullies when the sun is hitting them.

Snowpit from yesterday attached.   West aspect 9700'.  HS70, ECTP15 @ 23.

Some collapsing in the valley bottom, and also near the ridgeline- on both easterly and westerly aspects.  

Minimal wind effect.  Surface hoar to 10,000'.

From email: "Ernest and I dug a pit while setting up the yurt today, just off of the roundabout below the yurt. At 9410ft, NNW aspect, 10 degree slope, we found HS 75cm. The general structure seems right side up. There are facets at the bottom 20cm or so, but they are wet, and seem to be rounding. An ECT gave us ECTN20 at 40cm down. Here's a quick hand hardness profile. The bottom 20cm is slightly less hard than what's above it." Photo: N. Mattes 

We rode into Cabin Creek very delicately, and it was great to be riding in late November. Hitting rocks is the greatest threat. 

Overall conditions are thin but great to see so much snow.

9000 ft, N facing - 87 cm (~35 inches)

9100 ft, SE facing - 49 cm (~20 inches)

8100 ft, E facing - 35 cm (~13 inches)

Some faceting is occurring in the snowpack (aka - weakening), but the current state of the snowpack isn't the main issue. It's hard to appreciate how cold things are in the mountains and how cold the snow will get under clear skies. Clear nights in December will significantly weaken the snowpack, and it will look A LOT different the next time we come back. 

What we need? - Snow. We don't need a lot but a few inches every few days along with cloudy skies will help things a TON.

Where can you trigger an avalanche right now?  - I think you need to find a slope with recent wind drifts where you can either get a wind slab or persistent slab avalanche. 

Lastly - the radiation recrystallization process is happening as well. On an East-facing slope at 8100 ft at around noon, the surface of the snow was dry but snow just under the surface was damp. 

Snowpit from near Lulu Pass attached.  Localized collapsing on E, NE aspects between 9300- 9900', and no avalanche activity to report.

From email: "Northerly facing terrain harbors October snow, which has faceted. It is holding up plenty of dense snow and wind slab from the quite snowy and windy November. It was unable to hold the additional weight of a human trigger, and two pockets failed at the ground, which produced avalanches. Crown height maxed at 2’. Notably, where it did not avalanche, the failure propagated hundreds of feet down the ridge. It is a good data point- northerly aspects near tree line have potential instability."

Performed Stability test on Henderson Mountain today. Elevation 9600', SW facing slope. HS 85cm, New Snow 20cm. Of Note, 1mm Rounding/Moist Facets at ground with 1CM Melt Freeze Crust 60cm from surface. 1mm Facets on either side of MFcr. ECTN 6 at new/old snow interface and ECTN25 on MFcr 60cm down. Generally pretty good looking snowpack for November 24. No collapsing or cracking of the snowpack and no recent avalanche activity observed.

Localized collapsing and cracking yesterday on the upper slopes of Mt. Henderson, SW aspects.  HS ranged from about 30-75cms.  

Snowpit attached from a SW aspect about 9700', HS 50cms, ECTN9 @ 22cms (1-2mm facets above MF crust).

Flew from Paradise Valley to Cody and saw large plumes of our snowpack moving off of the peaks and getting transported from strong winds which were more southerly in the western part of the range and westerly around Cooke. Evidence of heavy cross loading across Sheep mountain (pictures) and the whole range, I didn’t see any evidence of avalanche activity. 

From obs: "I’ve been skiing the Erma Road recently. Good conditions for a quick ski up the road by but it’s thin off the road. The 616 trail is too treacherous for my comfort zone. I think the Republic Creek alpine valley must be skiable though. Quick observation:a sun crust formed in the open areas on the road and on adjacent areas."

Early season conditions. At 8000' just below the Sacajawea trail bowl, there is about 9" of snow. In the trail bowl, winds moved that snow around and there is nice firm, supportable (ie - not hitting rocks) snow. 
 

Warm weather really settled the snow and it became damp today on many sun exposed slopes. It stayed dry and cold on high north. 
 

Overall, the things seem quite stable, even though there may be a wind slab or two that could still avalanche. 
 

Drove up Lulu Pass road 1/4 mile from hwy 212. There was 7-8" of snow that fell since November 1 on previously snow-free southerly facing meadows around 8,100'. 

From e-mail: "Photo attached from near top of hyalite peak yesterday eve , 11/2. Cracking in recent hard wind slab, I had to really jump hard to make this. Walked on many other hard slabs that were well bonded. Highly variable snowpack. I think you'd be most likely to get into trouble by popping out a small hard slab pocket like this and getting magic carpeted into some thinly covered terrain."

Screenshots of webcams throughout the forecast area show new snow and snow cover on November 1. Snowfall last night dropped 2-8" throughout the forecast area.

-AM

1-3 mm faceting in front of the Montage. Clear skys and mid 20 temps