Snow Observations List

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.

We rode on Buck Ridge today to do some maintenance on our RAWS station for the fire folks and check on the yellow mule cabin.  Where the wind hadn't blown it away yet, there was 4" of snow from over night on top of very firm snow, likely from the last round of wind.  The most sheltered areas behind trees and down in the basins still had some deeper, soft snow and better riding.  We saw one small wind slab avalanche in the new snow above Beaver Creek on a north aspect. 

I toured up to hyalite lake today to check out how the west facing walls in the main fork of hyalite  (hyalite lake drainage ) were stabilizing after last weeks wind.  On Friday I noticed “Provo’s run” (large path near overlook mtn) slid from the top which appeared to have slid due to the heavy wind loading.  The slid looked to be about 24” deep and ran full path .  So today I checked out the west facing walls close the hyalite lake and around 9500’ the upper sections of these slid paths were wind effected and unstable, and I did not ride them 

I dug a pit around 9500’ on the west facing wall near the lake and got unstable results.  ECTP 11 which propagated below the recent wind load from last week.

the snow pack is 240 cm deep and is nice and consolidated without  any major layers on several of the pits I dug at several elevations on these upper elevation west facing walls accept for the wind load on the upper elevations pits 

We triggered and were caught in an avalanche very near town.  We skied the east side of Miller,  dropped down to descend the very eastern slope just above town. While standing on approximately a 30-35 degree slope we experienced a release immediately above us.  The crown line was approximately 18-24" and extended appx 50' across. We were caught for about 150' before coming to a stop and buried to the thigh. The entire slide was appx 400' from top to bottom.  It was appx a D2.

Today we toured to a ridge across from the west face of Republic Mountain. We observed multiple natural avalanches on several aspects. Winds were calm until around noon, and then picked up in the afternoon and were heavily loading north aspects at this location. 

From email 2/26/23: "I just talked with a fella that reported his buddy was buried up to his chest in an avalanche yesterday off of east abundance, near the cliffs. He reported a 4' crown and 200' wide. His buddy was snowmobiling."

Triggered wind slab in southern Gallatins

Experienced whumpfs, cracking, and remotely triggered collapses on E aspects at 9000’ near ridgelines. The wind slabs were very reactive but thin, ranging from 2” to 5” deep. 

From IG message 2/25/23: "Hey just wanted to report a Cooke city avalanche from today. Happened at 3pm caused by a skier coming down a south facing slope above Round Lake. Everyone was fine, he lost his skis and everyone learned"

From email 2/25/23: "... a good sized slab avalanche on Fan, NE Face. Crown height hard to estimate but looked like a 2’ or so. Maybe running on interface from when it got cold earlier in the week? Possibly deeper than that but sure could have loaded that much this week. Anyway- very white bed surface, good propagation, 200’ -300’ crown length, debris stopped on upper bench. D2.5. Likely triggered by cornice fall."

This natural avalanche was seen today on E. Henderson Bench.

On Saturday we toured up Sheep Creek and dug a pit on an SW aspect of Miller Mountain. We observed that the wind slab easily failed and propagated at this location. Shifting winds continued to load multiple aspects throughout the day. On the southwest ridge of Mineral Mountain we observed a large slide, approximately 200ft wide, that appeared to trigger another slide lower down on the slope. 

As we were skinning up a north facing slope on Knowles Peak, a roughly 20 by 20 foot section of the slope collapsed beneath our feet. We were on a slope steep enough to slide and it didn't, but we took that as a clear sign of instability and skied down. We then went up the south side of Arrow, mostly on mellower terrain before gaining the east ridge, and continued up. 400 feet from the summit we encountered a very steep, wind affected pitch, and decided not to continue up. We skied down the south gully, mostly in the trees and avoiding wide open slopes. South and east facing aspects were certainly heating up throughout the day and the ski down was hot pow. 

A snowmobiler saw this natural avalanche hit the Daisy Pass road within 10 minutes of riding by. He did a beacon search on the debris to confirm no one had been caught. It occurred about noon. This path is not very visible from the bottom and is not one that runs regularly. It killed a rider who was on the road in February 2012. The accident report has good photos of the path from afar.

Wind-loading in the start zone was the likely trigger since skiers and sledders do not access it.

From an email: "The crown was hard to see, but only looked a few feet deep where I could see it, but the debris pile was 10'+ on the road."

A big thanks to Dan Wykoff and Ben Zavora for providing the story and pictures.

We rode to Round Lake, Goose Lake wilderness boundary and Lulu Pass. We saw a coulpe of small and very steep avalanches that released in the new snow. We dug 3 pits and got ECTX or ECTN28 on the new/old snow interface 2-3 feet under the surface. We were glad to not find propogation. Wind ramped up during the morning creating white-out conditions at time. At Lulu Pass we went to investigate wind slabs and got a collapse (whumf) when we stepped on it. Wind-loaded slopes are dangerous right now. Slopes ae actively loading and sensitive to triggering.