Snow Observations List

Went looking for shallow and weak snow. Found it in the small steep slope just above the creek not far from the TH (HS ~80-90cm, fist hard facets near the ground, ECTP18).

Then dug near the top of Tyler's where it is typically weak. HS 103 cm, F+ hardness facets about a foot above the ground, ECTP28).

In Middle Basin we found snow depths of 150 cm and 200 cm. 

No avalanches seen and we had good visibility. (one group was skiing in upper Bear)

No collapsing or cracking either.

It seems unlikely to trigger avalanches on facets in deeper areas. It seems possible in thinner areas. How possible? Not sure exactly, but the odds are decreasing the longer things sit without more snow or wind loading. 

The primary concerns moving forward are wind slabs and storm slabs unless there is some major storm with a lot of wind and water.

Generally Moderate danger but we could be moving towards Low with time and depending on the weather. 

Snow quality  - lots of good powder, but lots of wind affected snow above treeline. Sunny slopes got damp today.

Saw cracking of cornices on the ridgeline NE of Mount Blackmore. Just a little nudge released a significant portion. A good reminder to give cornices room above and below.

Other than that, it was a beautiful day of skiing with sun, moderate temps, and pow. 👍

Things were really moving by mid morning. The trail along Unnamed Wall was buried in several places by wet slides as the wall warmed. Some were big enough to take you down. We did not see any movement on the other side of the valley.

Yesterday afternoon, 1/14, saw lots of roller balls and a few sizable sluffs come down around the dribbles area. This morning lots of small sluffs coming down around bingo cave as soon as the sun hit it. Noticeably heavy, wet snow on solar slopes as well.

This avalanche was spotted from the air on Wednesday, Jan 15 on Red Mountain in the southern Madison Range (just west of Ernest Miller Ridge).

It appears to be on an east facing slope at around 9800 ft.

We rode into Portal Creek to the ridgeline above Hidden Lakes and back below Windy Pass. During our ride, we noted no avalanche activity or signs of instability. We dug twice to the ground. Once above Hidden Lakes and once in the corner of an avalanche path below Windy Pass. 

Bottom Line: 

• The snowpack is DEEP. The measured HS was "1 Dave" or 6'5" (200 cm).
• Stability is looking good in our pits, and we are optimistic. 
• ECTNs-mid teens within the layers of the post-Christmas storm snow. 
• Faceted snow near the base of the snowpack is hardening and rounding. Even with extra prodding (deep taps and an unofficial cross-slope PST), we couldn't get it to break or propagate failure.
• The mountain range is expansive, and one must assume spatial variability on both slope and certainly the range scale, but this is good. 

Big Picture: 

• Other than one avalanche that appeared to break on persistent weak layers below Maid of the Mist, Ian and I couldn't think of another persistent slab avalanche in the Northern Gallatin Range. 
• Wind Slab avalanches are the most likely issue.
• Danger is dropping quickly. 
• We don't trust facets often and aren't ready to write off the basal weakness, but triggering an avalanche on these layers seems unlikely for now. 
• This puts wind slab avalanches as the primary concern... and it hasn't been very windy. So, this seems limited for now. 

Terrain Recommendations:

• It is appropriate to consider riding and skiing in avalanche terrain if one is willing to accept the inherent levels of uncertainty involved with steep, backcountry terrain.
• We are pessimistic by nature and like to hedge our bets. The way to do this is by selecting terrain less likely to avalanche (not as steep, more uniform in depth—less rocky, potentially shallow areas, and not wind-loaded) and terrain with lesser consequences (smaller slopes, fewer terrain traps, clean runouts). 

While driving to and from West Yellowstone today, I noticed what is potentially a skier/snowboarder triggered avalanche on the east side of HWY 191 on a West/Southwesterly aspect, directly across the highway from the Bacon Rind Area and Snowslide Creek.  There were numerous tracks through steep rocky chutes next to the road, one of which had avalanched perhaps 75' wide, 18-24" deep, and running nearly to the flats at the base of the slope.  Judging by the thin layer of fresh snow it potentially happened on Sunday or maybe Monday.  There were tracks through the cliffs above the slide and coming out of the slide.  

On our way up Mt. Ellis, we noted widespread surface hoar on east facing slopes above ~7000', especially in open areas. Grain sizes ranged from 1 mm to 3+ mm at higher elevations. Winds were calm almost all day, even while on the skin track along the ridgeline. Given another 1-2 days of clear, calm conditions in the weather forecast, these surface grains could certainly continue to grow in size before the next storm.

We dug a pit on a south facing slope just below the Mt. Ellis summit. The snowpack on this solar aspect (77 cm) and not quite as deep as on easterly aspects. Although we found some basal facets in our pit, the bottom layer was stronger than we expected. We did not get propagating results on any layer with our ECT. Afterwards, skiing conditions on eastern slopes were excellent.

Spotted another natural avalanche today on Woody Ridge north of the "KNBs." Northwest facing slope, crown elevation approx 9600'. Ran 1000 to 1200'. Unsure of when it went, we did not notice it this morning only this afternoon on the hike out. 

On 1/12 observed a D .5 soft slab near Long Lake above the snowmobile trail. Also saw some small dry loose activity on E facing terrain in Zimmer Creek. 

18 inches of powder at the East Fork Divide. Overall, found about 4 feet of snow. Rocks lurking slightly under the snow surface in some areas. Base was pretty solid - a surprise. There is a faceted layer at the bottom but the snowpack was pretty consolidated and fun to ride with good traction. Did not see any fissures or cracks in slope and dust feel any collapsing slabs during the ride.  

Skied the third meadow and dug a pit this morning. Calm winds with no evidence of previous winds around 8500'. S1 in the morning which ceased as skies began to clear midday. No signs of instability were observed.

Our pit provided several ECT results on multiple interfaces, which we were curious about after this previous storm cycle but were surprised by the lack of propagation/quality in our results.

Travel conditions have improved significantly since the last time we were at Bacon Rind, unfortunately, avalanche conditions have not. Similar to what Dave and Alex saw yesterday in Lionhead, the snowpack on Bacon Rind is shallow and has well-developed persistent weak layers near the bottom of the snowpack.

While ascending the burn, we triggered so many thunderous collapses that we quickly lost count. These collapses shook snow off the trees around us and visibly dropped the snow surface beneath our feet. Near the top of the ridge, we saw a large avalanche (SS-N-R3-D2-O) that broke on a north facing aspect, around 2' deep, on weak snow near the ground. It was not clear whether it was one large avalanche or two that released sympathetically with one another. If one slide, this avalanche broke nearly 900' wide and slid around 1000' vertical. It broke during the most recent period of intense loading in this area, likely January 5th or 6th. 

When we reached the top of the Skillet and dug a snowpit, we noticed that the upper portion of the path had cracked and shifted in numerous places but had not avalanched. Our snowpit on an east aspect showed a 2' dense slab on top of sugary facets and depth hoar. Our test result was ECTP 13. We also dug a pit on a south facing aspect and noted shallower snow that was slightly stronger than the other aspects we had seen thus far (north and east). 

Given all these clear signs of instability, it was an easy decision to stick to terrain less than 30 degrees, including runout zones. 

S-1 snowfall most of the day, with calm winds. Skies began overcast and cleared throughout the day. 

We rode below Lionhead Ridge via Denny Creek and found a snowpack with the worst structure we've seen in our forecast area. There was around 3 feet of snow on the ground between 8000-9000'. The bottom foot was sugary weak facets, and the upper snowpack was a supportable hard slab with new snow on top (profile attached). 

We had two large collapses. The most significant collapse happened when we were leaving our snowpit and walking back to our sleds a few feet away. We heard a long "whumph" sound and saw our snowmobiles drop an inch, as the snowpack on the entire slope around us collapsed. Our snowpit had ECTP23 x2 breaking on the sugary weak layer.

We saw 4-5 avalanche crowns that were up to a week old, some had been reported and a few we had not heard of (3 pictured were previously not reported to my knowledge). One was a 3-4'+thick slab on a rocky heavily wind-loaded slope off Lionhead ridge, and the other two were ~2' deep on less wind affected slopes lower down in the trees, but probably had some previous wind-loading.

Despite no fresh avalanches the last few days, the poor structure and collapses suggest a person could easily trigger a large avalanche that breaks wide on the weak layers at the bottom of the snowpack.

There was evidence of recent winds in the meadows with thick drifts felt while riding and some ridges scoured free of recent snow. Skies were mostly clear and wind was calm today.

Headed out to the throne today. Had light to moderate winds from the west blowing all day long at all elevations. Found heavily wind affected skiing in open meadows and softer snow in the trees. Stayed out of avalanche terrain and found no signs of instability. Snow was visibly being transported all day.

Toured into the basin NE of Ross Peak this afternoon.

Snow depth in the basin was 115cm. Winds predominantly from the SW.

Light to moderate snowfall throughout the afternoon.

No avalanche activity noted, but much of the ridge line was obscured by clouds. 

No collapsing or crack propagation seen.

Observed a large avalanche on a west facing slope approx 10000ft, with a higher crown at 10200'. Crown depth 4-6'. HS-Ns-D2-R2-O . Ran 1000ft and into terrain I had previously considered safe.

Toured up Sheep Creek Trail on the West side of the Lionhead Range on 1/11/2025. We heard whoomphing through out our tour in. We stopped counting after 12. Some of these whoomphs seemed relatively far away and very loud. We could not tell if these farther whoomphs were triggered by us. We were the only ones in our location but we did hear snowmobiles in another location near the trailhead. We also felt multiple large collapses on very low angle slopes and skinning across non consequential terrain. 

We dug a pit on an East facing aspect below the slope we had planned to ride. The height of snow was about 110 cm and there was a very concerning layer of large facets at 75cm deep going to the ground. There were no other layers of concern in the snowpack we found and the rest of the snowpack was right side up. Our results were CT17 SPQ2 and ECTP26 SCQ1. Bother failures during tests were on the layer of facets and on the CT and ECT our columns easily separated from the facet layer after failure. Due to these observations we opted not to ride our objective and followed our skin track back out to the trailhead. 

3x ECTX on NE facing 7,400ft. 15cm of new storm snow. Moderate SW winds with strong gusts. S2 from 11am -1pm, S1 snowfall beginning as we exited the field (1530). Blowing snow observed throughout the day.