20-21

Skied the west side of Hebgen Lake today from Kirkwood trail. Mostly overcast to broken skies with very light west wind and light snowfall all day. Temps probably mid 20s F. 3-4 in of new snow down lower, with 5-6 at upper elevations. Coverage was adequate but lots of sharks, especially low.

Experienced widespread whumpfing and shooting cracks on east facing terrain from Lake to over 9000 ft. Dug a pit at 8300 ft. Profile attached. Very weak snow with little structure, but the midpack had a distinct density change with 4F hardness. Large facets close to being depth hoar (~3mm) developing at ground. ECTP17 at the top of this basal layer. My friend also did a PST in a nearby pit and got propagation at 20cm/120cm on the same layer.

This slide was triggered remotely, from low angle terrain, on a 9100’ SE aspect on a 34-35 degree slope. It was a 1.5'-2' deep soft slab (4F+ to F hard) that broke on weak sugary facets.

Skiers triggered this avalanche remotely, from a distance on 1/2/2021. It is on 9100’ elev. SE aspect in Yellowstone N.P. outside of Cooke City.

I toured up to divide today and ascended the lower east shoulder of divide pk
There were no obvious signs of instability so I ascended the Low angle terrain to the north east of the pk
I dug 2 pits on my ascent one propagated at the ectp17 and the other at ectp25
From these results I keep off any of the small roll overs or steeper pitches of that east flank of the pk and just road the 30 deg terrain to far lookers right of the pk
I was up there two weeks ago And would not ski due to instabilities but the stability is improving but still can not be trusted

Yesterday I saw two tracks center punching directly off divide pk
I feel that person was totally rolling the dice

I did not ascent any slopes that were connected to steep terrain and keep the angle at 30 deg
The snowpack in hyalite can not be Trusted

Today in the southern gallatin we found widespread poor structure (surprise) with the bottom 30 cm of the snowpack consisting of FC and full on DH. Moderate winds were rapidly drifting the new snow, and anywhere with a new load/slightly stiffer slab was collapsing, with shooting cracks, remote triggers of shallow wind slabs, etc. Some of the collapses ran for over 30m. We were BTL, but I expect that at and above treeline wind slabs were touchy today, with remote triggers possible. Many areas still lack the load necessary to make large avalanches but that time is coming.

Seemingly unsafe snowpack here in island park. A few very firm crust layers. One facet layer near the base which propagated. Two crust layers, both knife hardness, were stacked in each other with a small amount of facets between them. This layer went on CTE 8. I wasn't able to attach it but I will send it separately. We weren't in avalanche terrain today so there were no other observations.

Hi guys,

Toured out towards Hyalite Peak today and skied the open slope that is below Divide Peak, just across the creek from the summer trail.

Snowpack resembled everywhere else - weak facets under a 4F/4F+ slab and some soft new snow. In our pit, we got a CT20 and ECTN22 that broke on the basal facets but did not propagate (slab broke apart). We dug 2 more quick pits looking for a harder slab as we moved higher on the slope but the snow structure felt the same. Had one isolated whump on what was likely a wind loaded terrain feature, but otherwise no signs of instability. Stayed off the steepest parts of the slope and the skiing was excellent.

Mike