Snow Observations List

Toured wolverine bowl and noticed a couple of large slides near the ridge on NE aspects. The most obvious was this one on hourglass that looks like it went in the last week.  Trigger could have been part of the massive cornices breaking off.

from text 3/3/23: "[talked to some skiers in the coffee shop] saw multiple natural avalanches yesterday [3/2] on the north side of Miller in Abundance...."

Hi,

My partner and I toured up the south fork of deep creek and skied the lawnmower on town hill. Conditions were variable, we found good snow in the upper portion of the lawnmower but the mid to low elevations were extremely scoured and/or icy. Snow along ridgelines had been drifted into thick, very hard slabs. We dug a pit at 9000', NW aspect. HS170, ECTPX. The snowpack above the weak, sugary facets near the ground seemed generally right side up and stable. No cracking or collapsing except for a thin layer of what looked like near surface facets or surface hoar in the top two inches. We kicked off many small, inch to half-inch thick wind slabs on our way down, that only propagated a few feet out while skiing down. We weren't concerned given this weak snow was confined to the very top of the snowpack, but it could be an issue in the future. Near the bottom of the slide path we saw one small wind slab avalanche that was likely skier triggered, but that was the only avalanche activity we observed. Hopefully this info is useful. 

We skied to the east face in mostly calm conditions. Last night's 2" of new snow was not blown around. We could still see the crown of the natural avalanche that broke on Friday, 24 February. Skiing across wind drifts produced no cracking. We dug off the ridge on the east face near the first line down. HS was 215 and we got an ECTN 11 at 195 cm. With a load of new or windblown snow this layer could propagate, but not today. The snowpack consisted of multiple layers of wind slab which was not surprising given the location.

From email: Hi, I noticed the slide that went over the Daisy pass road was labeled natural. We rode over it in the afternoon around 5pm and it hadn't been there when we went over the pass early that morning. We heard from a couple of other snowmobilers that some folks had been skiing up there, parked a sled at the bottom for their lap, then triggered the slide by ski cut before they dropped in. The slide buried their sled and they had to dig it out. Here's a few photos that I took that afternoon."

From IG message: "Yesterday on March 2nd we were on the trail to daisy pass just before the bowl in cooke city. There were 12 of us of us no total. Just behind us a large avalanche came down covering the trail and clearing trees on the way. We went to investigate to make sure there were no burials when 2 skiers came down and said they were stomping on the facet layer and triggered it intentionally. The slide swept the skier’s parked snowmobile off trail and carried it about 100 feet."

From email 3/3/23: "Another natural avalanche that ran across the road near Daisy pass last night. Our groomer took this picture. I was also informed that some skiers triggered an avalanche near Daisy yesterday afternoon. No other details on that. This would be a w/SW facing slope."

After further investigation: "It is the same avalanche that the skiers triggered. Crown looks 5-6' deep, 150'+ wide and SW aspect."

We observed a couple more natural avalanches on Miller Ridge today.  NE aspects, around 9800'. 

There was about 15” of storm snow. One of the slopes in Sage Basin avalanched with a large cornice trigger. The slide failed 85 cm deep (~3 feet) on a layer of surface hoar. The surface hoar was a surprise as we haven't seen avalanches on this layer for a long time. I got an ECTP27 in the flank, and it failed on the same layer of surface hoar as the avalanche. I would recommend minimizing time on wind-loaded slopes or avoiding them all together. Weak layers buried 3-4 feet deep are back in play, and I wouldn't ride a steep slope without testing them quickly. 

Yesterday and today from the the Throne and Fraiz area: with no wind we saw no signs of instability. The biggest challenge is the parking at Battle Ridge. Carefully asses your line before committing to entering the parking area and be prepared to fall back to a less ambitious parking plan if there are more than a couple of rigs already there. 

This morning at 11am we saw a very large avalanche crown on the east side on Henderson Mtn., in the big avalanche path off the highest summit. It likely occurred late yesterday or early this morning. There was minimal new or drifted snow covering it, and it was snowing and blowing yesterday all day.

I estimate the crown is 6-8 feet deep, possibly 10 feet in spots. Measured on GoogleEarth to be 700 feet wide. 1200 feet vertical. HS-N-R3-D3-O. It did not go to the ground. Given how much wind-loading this path gets it may have been near the interface the 6 feet of snow that fell over the last 7-10 days, but it easily could have broken on a variety of faceted layers deeper in the snowpack.

Today wind was very calm and skies were partly cloudy. We saw a few shots of blue sky mixed with a few snow showers that totaled maybe 2-3cm.

NW aspect 8900’ 

HS 175cm

ECTP11 @120cm on 4F facets

This test result changed our intended plans and we decided to stay off steep slopes. We experienced intermittent light snow and light wind all day. 

We rode to Ski Hill and dug. HS was 230cm and the top 60 cm was from last week. the top 25 cm was F hardness powder. No wind when we were there. We got an  ECTX. We then rode to the old weather station at 8700' and had HS 210 cm. Same layering but got ECTP20 about 65 cm down at the interface of the old snow surface and this weeks deposit. I looked with a hand lens and did not find facets, just a density change. But with the top foot being F powder it would not take much to build drifts that would slide. 

We also saw one small slide on the drive on a roadcut a Fawn Pass that looked to be 1.5' deep and 50' wide, soft slab. 

Pretty mild observations:  north ridge above Hebgen, some woomfing on the ridge pretty subtle.  This was yesterday morning, on the ridge top.  Tons of new snow.  Also point release in the slide area, north face of slide scare, above quake lake, visible from the road new in the last couple of days.  Obviously natural trigger there.  

I had heard a rumor from snowmobilers that there was a human-triggered avalanche on Lionhead on Thursday the 23^rd.  While in Taylor Fork yesterday, we ran into one of the individuals that was a part of the incident. The jist of it was he and a buddy were climbing together, and he uncovered a rock that his buddy then hit.  While the first rider continued to climb, he triggered a slide, and it partially buried the second rider.  He was able to deploy his airbag but was carried approximately 100 yds down the slope where he was buried.  Other members of his group quickly found him. 

I think this natural avalanche happened about 24-48 hours ago.  (pretty sure it wasn't there 2-3 days ago?). It's an E, SE aspect, about 9200', between Cooke City and Silver Gate.

A group watched a natural avalanche from the Pilot Creek Parking area cascade down the mountainside on Friday, 2/24/23 at 5:00 PM. 

From IG. “I spotted a large crown this morning on the E face of Bole. The crown appeared to be pretty deep, at least a few feet, and propagated quite wide. It also looked like there was a debris path coming down the apron of the E face of Hyalite peak, but I was too far away to know for sure.”

We rode to Henderson Bench and dug a pit on a northeast aspect at 9,400'. We had ECTX x2. Last week's snow had settled to about 2.5' and was well bonded. There was one harder wind blown layer in the middle that created an upside down density change, but it did not react in stability test. Total depth was 266cm. We measured 0.65" SWE in the top 10" of snow which we assume is what fell since yesterday morning.

We rode over to Scotch Bonnet and dug on a SW aspect at 9,700'. We had some ECTNs near the middle of the last week's snow, and 2x ECTP29 on facets down 3.5'. We did not see any obvious stability concerns in our pits, but the large amount of snow and wind last week followed by many avalanches is enough to keep danger elevated for a couple more days, especially with continued snowfall and/or wind-loading.