Snow Observations List

The skiing was good and non reactive on the main East face next to the skin track. The North gullies into Naya Nuki creek and the the lower/steeper gullies to the south were highly reactive and entraining lots of snow.

We toured up to Mt Blackmore today and found that winter had returned to the high peaks over the last two days. Since yesterday morning, high elevations around Hyalite have received about 12" of new snow (1.2" SWE). The parking lot had around 3", the trail around 6" and at elevations above 8500' the numbers corresponded well to the Shower Falls SNOTEL.

The parking lot and lower trail softened up throughout the day and temperatures were above 32 degrees at the car at 3pm. In the alpine around 9800', temperatures were just below freezing (31 degrees) around 1pm. Despite our layers and gear getting a bit soggy, the snow from last night remained dry.

A mix of rimed precipitation particles and graupel fell throughout the day. Previous and current winds were calm; there was little to no wind effect on the new snow. we saw no cracking or recent drifts. The 12" of snow since yesterday fell right-side-up and had little to no slab properties. This new snow rests on a stout melt-freeze crust from the high temperatures last week.

Our main avalanche hazard today were dry-loose avalanches. Despite lots of traffic in this zone today, we only saw a handful of slides in steep terrain, and all were relatively small and did not entrain much snow. Conditions can and will change quickly if winds increase or the sun comes out and warms the new snow, but for now, we were happy to find good powder skiing. 

Skied the Banana today with 8-12” of new snow that has mostly bonded. The snowpack below the new snow had froze over night and was well consolidated. 

Observed a layer of graupel (3-4mm grains) at the new/old interface on the NE ramp starting at 8600’ and clearing up after 8700’.  This layer created some reactivity in the storm snow.
Wind slabs <6” had formed on N and NE aspects. We had one small release in the bottom of the couloir measuring ~10x20’ and running ~50’. 
 

Other than that, the skiing was amazing and manageable. 

Toured around Beehive and Middle Basins this morning, finding predictably bulletproof snow on most aspects but decent turns aided by the 2-4 inches of snow from last night on northerly terrain that hadn’t been destroyed by the sun this week. There were a few brief moments of direct sun throughout the morning, which almost instantaneously triggered point releases from steeper rocky terrain. On the way back through Beehive we observed some much larger debris piles that weren’t there this morning from the steel rocky face between the Going Home chute and the prayer flags. 

We rode into the Taylor Fork, up to the weather station, and out towards the wilderness boundary. Temperatures were around 40 degrees at the car. There was a surficial refreeze last night with a skiff of graupel on top. With mostly sunny skies and calm winds the snow surface dampened quickly. 

We dug down on two sunny aspects (E-SE) and noted moist snow throughout the snowpack. In our first snowpit (9220', HS:108) we did not get notable test results (ECTX). We found that although faceted snow remains at the base of the snowpack, water has percolated down and moistened these basal layers. 

We also dug on a NW aspect (8800', HS:199) with no notable test results (ECTX). Moist snow exists in the upper 1.5' of the snowpack with dry snow to the ground. 

We noted no cracking or collapsing. We saw a good number of wet-loose avalanches on steep sunny slopes, but all were relatively small in width and depth. 

We skied Saddle as early as we could after the lifts opened, but we were still a bit late, and/or there was limited overnight refreeze, I suspect more of the latter. Clear-ish skies overnight had me optimistic, but warms temps seem to have dominated below 9000 ft.

The first 100 vertical feet from the summit skied quite well where a thin melt-freeze crust was just starting to break down. Overcast skies and L-M winds likely limited warming. Below 9000 ft we poked around and found the top 15-20cm was moist and unsupportive on NE-SE aspects. We kicked off numerous roller balls but no actual loose wet avalanches. 

The best skiing was in previously skied areas, such as the guts of going home chute, or in-bounds.

We rode up to Fairy Lake area today and quickly found out just how warm it has been in this area the last two days. At the trailhead at 10am temperatures were around 47 degrees. Last night, it did not freeze below 9000' and an isothermal snowpack now exists from the trailhead all the way to Fairy Lake and above, until you pop out into Airplane Bowl. When we returned to the trailhead around 2:30pm, it was 65 degrees at the truck. 

While higher elevation southerly and easterly snowpacks were warm and wet, free water was only moving through the upper few inches of the snowpack by 1pm. High elevation northerly aspects remained colder and more locked up than we expected given the ambient air temperature. Winds were light from the W and were doing little to keep surfaces cold.

There were a number of wet loose avalanches in Airplane Bowl when we were heading out around 2pm. All on E/S aspects near rocks or cliffs. Most were relatively small and had not entrained much snow from the surface or gouged deeper than a few inches. 

On the drive back to town, we noted 5 or so larger wet loose avalanches in Argentina Bowl, with a good number of smaller slides at different points along the ridge

Seeing as it is now the season for wet snow hazards, there are a few things that are critical to consider: aspect, elevation, and timing.

Timing your day to be off of steep slopes before melt water percolates too deep and destabilizes the slope is key, AND making sure to account for steep low-elevation slopes that you may have to pass through on your way back to the trailhead. If you start to sink in deeper than your ankles, or your sled track is digging into slush, that means it is time to either shift to colder aspects or head back to the trailhead. 

Our greatest concern with these wet loose avalanches is not so much their size, but their power to push you into terrain traps like cliffs, gullies, trees, or rocks. The two scenarios when we are most concerned about these avalanches are when new snow gets wet and sheds for the first time OR when there have been multiple days without a solid refreeze and melt-water percolates deep into the snowpack. 

We skied past a wet loose avalanche that came off of the south face of Bradley‘s Meadow. It was slightly bigger than the rest of the wet snow activity that I observed during the day. 

We rode around the far end of Buck Ridge today (Bear Creek, McAtee, 2nd Yellow Mule) and found very warm temperatures and increasingly spring-like snow.  Almost everywhere at upper elevations there was a thin melt-freeze glaze on the snow (except in deeper shade and lee areas where the weekends wind pushed snow).  Below the surface 4-6" the snow was still fairly dry too.  We could see a few point releases from yesterday's warmth in steeper and rockier areas but otherwise no avalanche activity up high.  The riding ended up being surprisingly good still and the bottom 3 miles of Doe Creek Rd are snow/slush/ice covered for now.  That will not last much longer.  

On the drive home in Gallatin Canyon, however, we did see some wet slides in the chutes/gullies south of Lava Lake (photo attached).  

Today we noticed these natural small wind slabs on Mt Henderson.

We also observed active wet loose in Zimmer Creek today on rocky terrain. 

Noticed crown and debris on drive up Bridger Canyon this morning.  Looks like a wind slab. 

Today, Dave and I did the full mechanized boundary tour north of Cooke City. We rode up and over Daisy Pass towards Wolverine Pass and Mount Abundance, up Lulu Pass, to the Goose Lake boundary, and back out through Round Lake.

In thirty miles of riding, we noted one avalanche on the Fin that likely occurred yesterday or early this morning from a wind slab or cornice fall. That being said, low cloud cover obscured views and the light was relatively flat all day. What was visible were strong winds transporting snow, especially at high elevations. We chose to stay out of steep upper elevation bowls that are regularly wind loaded and out from under corniced ridgelines. 

As we rode, we dug a few snowpits looking for the weak layer that we found yesterday buried about 2 feet deep. While we were able to find this layer, we only got propagation in one of three tests (ECTP 26, E aspect, 9070'). 

Throughout the day, the snow surface became denser and denser. The little precipitation that fell was noticeably rimed and when we rode back into Cooke City around 1pm it was nearly 40 degrees in town. Driving out of Cooke and into the Lamar Valley, we saw a good number of wet loose avalanches breaking in steep, cliffy terrain just south of the road. 

Looking ahead, we are preparing for a sudden shift in the weather with above-freezing temperatures into the alpine and direct sunshine. We are keeping an eye on wind slab avalanches at upper elevations, but will start to shift our focus towards the potential for wet snow avalanche problems in the coming days. 

Fin had a slide on it today. I was too cloudy to tell if it was released naturally or not.

Photo of a recent natural avalanche north of Cooke City, observed today.  A S, SE aspect in Sheep Creek at about 9000'.   Seems like it likely occurred yesterday.

Estimated to be about 2' deep at 250' wide.

Winds were ripping on the hike to Saddle Peak - almost knocking us over. If they had been just a few mph stronger, we would have been crawling. They were still finding snow to transport, and there were obvious plumes at discrete points along the ridge. Much of the snow was being blown to North Dakota while loading only in isolated places. 

As soon as you got off the ridge, winds dropped to almost nothing, and we didn't find any wind slabs as we descended off the nose of Saddle into the North Central Gully. The skiing was excellent.

Further south, the bare rock area north of Bridger Peak had grown significantly as winds scoured a much larger area down to rock.

We rode up to the east Henderson Bench and back around to Scotch Bonnet and the Rasta Chutes. There was 5" of low-density new snow throughout the day and strong winds were actively drifting snow. Instability in the upper few inches was evident, with shooting cracks and small avalanches on steep drifts. In terrain unaffected by the wind, loose snow avalanches in the top few inches slid easily. 

We dug on a northeast-facing slope ("Almost Died"), and two on southeast-facing slopes at two elevations in the Rasta Chutes. There was a recently buried weak layer 20-30 inches deep in all the pits that failed and propagated in two out of three--both the SE Rasta Pits (ECTP21 & ECTP25). I don't think we'll see a widespread avalanche cycle on this layer, but it is worth digging for and assessing before considering steep terrain. We saw Beau Fredlund at dinner and he came across an avalanche in Sheep Creek that broke 2-3 feet deep and 300 feet wide. I suspect it was this layer; however, the slope that avalanched was different in that it was a thin snowpack with some grass poking out. Our pits were 250-350cm DEEP! 

The bottom line: 

• Significant amounts of recent snow and strong wind this afternoon, and more snow forecast for tonight. Avalanches on wind-loaded slopes are likely to very likely. Currently, I would avoid all the big, heavily wind-loaded terrain in Cooke City. This is were you'll trigger a slide and it has the potential to break a few feet deep. 
• Dig down three feet to test for instability before skiing or riding steeper non-wind-loaded terrain. 

We got an ECTP18 result on a north aspect at 8600’ in the absarokas. It propagated on a small layer of facets 30cm down. We did not get any collapsing nor see signs of naturals or other activity on this layer, but we stuck to non-wind loaded slopes in the trees. 

Skied south of Cooke today. Got an ECTP28 down 80cm on small facets above a MF crust that was buried on March 14. West aspect at 9500'. While filling in the snowpit I got a large collapse. This is the same layer we were getting ECTP results on earlier this week north of town. 

We rode into all three Yellow Mule drainages and the head of Muddy Creek. It was snowing hard and wind was blowing strong this morning. In the afternoon, clouds lifted and snow let up. Skies remained mostly cloudy, but with high clouds there was decent visibility at the end of the day. There were 10-12" of new snow since last weekend, 2-4" low density fell this morning.

There was a small wind slab avalanche in McAtee (Photo) and a small wind slab in Beaver Creek. 

We dug four snowpits, northerly aspects (one in each Yellow Mule), and one on a southeast aspect on the west side of the Second Yellow Mule. We did not find any unstable test scores or concerning layers. ECTNs within the new snow and ECTXs in some cases. In the southeast facing pit there was one .5" thick crust below this week's snow and a crust 2" thick below last weekend's snow (photo). Most pits had a dirt layer from last Sun/Mon strong-extreme winds, 10-12" deep. Total snow depth was 6-7 feet.