Snow Observations List

Observed some cracking in wind drifted snow above tree line NE facing slope. No avalanches observed 

Dug a pit at 9650ft on a 20° NE facing slope near Zimmer Creek. HS 210-230. ECTN14 at about 40cm down.  

Today we observed wet loose avalanches in steep, rocky terrain on the west side of Miller ridge. SW facing, 9500 ft

Snowpit attached from Mt. Republic today.  East aspect, 10,000'.

HS 165, ECTP22 at 65.  

No collapsing, no cracking, no avalanche activity to report.  

40 deg F at Fisher Creek SNOTEL today (9100').

Snowpit attached from an east aspect at 9400', south of Cooke City today.

HS 250 cms, with the Feb. 3rd dust layer about 100cms from the surface.  EXTX.

Below the dust layer there were 1mm rounding facets, that were 1F hard.

No avalanche activity observed, with LOTS of looking around.  No collapsing, no cracking.

Temps around 40F in the valley, but minimal wet loose activity observed so far.  The warmup has been gradual the last 2 days, with good freezes at night.

Also, there was a wolverine up on the mountain this morning!

Riding in this morning, we saw this older wet slide on the Portal Creek road down low at about 6400' in elevation on a south facing slope by lots of exposed rocks. For reference, Gallatin River is 5800' in this area.

We didn't see any fresh ones on our way out at about 2:30. 

The most likely places for big wet slides are slopes or areas with exposed rocks and cliffs. Generally these wet slides happen a little predictably in the afternoon as the snow gets wet. We know what time of day they'll happen, but it's hard to know exactly when they'll release, so watch out when the snow is obviously wet if traveling under slopes like this. 
 

You don't need to worry about them in the morning, when the snow is frozen. What a nasty avalanche with sticks, rocks, and dirt in it?

Fresh wind slab avalanche seen this afternoon, possibly rider triggered.

We received a call (from a third party) about a snowmobiler that was buried with their head 5 feet below the snow and their foot sticking out of the snow. Their partners saw the foot and dug them out. The riders face was blue, but quickly became responsive after a "chest thump". 

They were riding on the north side of Miller Mtn. Given the widespread winds and drifting, we suspect it was likely a wind slab avalanche similar to one spotted on Crown Butte the same day.

We went to look at an avalanche that was triggered two days ago, remotely from flat terrain above a steep slope, on the northeast end of Mt. Abundance. While looking for the avalanche from the flat bench above we triggered a similar sized slide directly adjacent to the previous slide. They broke on weak layers of facets and surface hoar that formed at the end of January. 2-3 feet deep and 150-200' wide. 1F to P- hard slab above the weak layer with 25cm of 4F to F snow at the surface. AFr-HS-R3-D2-O.

We also saw at least 3 rider triggered wind slabs, 4-5 natural wind slab avalanches, and a couple large cornice falls.

Strong wind had affected almost every piece of terrain, scouring some slopes, loading others, just stiffening the slab in many areas, and forming fresh drifts on every convex roll and along the edges of trails. Riding was still soft and fairly consistent in many areas.

I expect wind slab avalanches will be easy to trigger for a day or two more due to how reactive drifts were today... and it is still blowing and snowing a little more tonight.

The persistent slab avalanche problem is tricky because we have not seen any other avalanches of this type near Cooke City and it seems isolated, but slopes that harbor that instability might have just reached a tipping point with this round of wind-loading and dense snow, so it seems possible we could see a couple more of these avalanches over the next couple days or later this season. It will be a good idea to step back from most slopes steeper than 30 degrees during this wind-loading event, especially slopes with larger consequences like trees, cliffs and just generally large steep slopes.

Today I saw a very small wind slab on Republic Peak. Crown was 10 feet wide. No other avalanches observed 

Observed a snowmobile triggered avalanche today. East facing slope, approx 9700', between Fischer Peak and LuLu pass. Rider was not caught. HS-AMu-D1-R1-I. Observed lots of wind transport and loading from strong w/sw winds today. 

8761ft

43 NE

13 degree slope

HST 125

ECTP 12 50 down

Soft snow ski pen 30 cm

supportable pow

clear skis tell 11:20

11:20 few

We went up Republic Creek to look at the stability of snow that has fallen over the last 2-3 weeks. Skies were overcast with light snow falling most of the day and winds were moderate with strong gusts.

We found a thin layer buried 2’ deep that showed potential to propagate and slide. We dug down 4 feet, just below the dirt layer that was deposited earlier this month. We got an ECTP30 that broke about 8" above that dirt layer. This was either on a thin layer of facets or preserved lower density dendrites.

We heard of an avalanche that was triggered yesterday which broke 2’ deep and 250’ wide, possibly on this same layer, on an east facing slope by Mt. Abundance.

The wind was blowing new snow into fresh wind slabs. We were able to easily to trigger a couple wind slab avalanches on test slopes. More snow is expected tonight and tomorrow which will increase the likelihood and size of wind slab avalanches, and the added weight could cause a 2-3’ deep avalanche to break a couple hundred feet wide. Be cautious of steep slopes as new snow and wind build slabs over the next couple days.

A rider triggered a slide on Saturday (2/22) on a bench below the east face of Mt. Abundance... Trigger point was from the top while driving by. 2' deep, 250' wide??

Today we observed a couple day old wind slabs in steep SW facing terrain on Mt Zimmer. Also, a wet loose occurred sometime today between 11-2 pm on S facing terrain nearby 

Very deep snow past Round Lake today. New snow ranged from 2-4’ deep. My elbows and shouldered were touching the trenches of my sled track as I rode through Star Lake toward the wilderness boundary. New snow was very low density. No natural avalanches observed and ski cuts were non reactive on test slopes.

Traveled up Republic Creek, ascending to ridge separating Wyoming and Republic Creeks. Trailbreaking was arduous, ski pen ~ 60-80cm depending on travel under canopy or in more open terrain. Did not formally evaluate HST, suffice to say it was significant. HS 260cm at 9600ft. Skies obscured all day with varying snowfall rates, S1-3. Moderate W/SW winds and PLENTY of transport. Observed a D2 natural (wind/storm slab? Hard to say from my vantage) on E aspect at ~9200ft. A member of our party intentionally triggered a 30-40cm storm slab on a small convexity in treed terrain in Wyoming Creek. No other natural or skier triggered activity observed, though visibility limited our view to the more complex terrain further up Republic. Ended the day with a Woody Ridge lap and encountered no cracking/slabbing of new snow in this zone. Snowfall was intensifying as we left the drainage around 1700.

After taking a heavy landing on top of a pillow just off the highway past lolo pass road, I looked back up and could visibly see some layer distinction about 8-12” deep. This is the same weakish layer we found in our column test, where we got ect16 just below robs knob. This was on a north facing aspect.

In Hayden Creek, we saw many D1-D1.5 wind slab avalanches seen on leeward slopes- east and northeast slopes at and above treeline. We observed cracking in wind loaded areas above treeline. Dug a pit and did a quick ECT on E facing terrain at 9750ft. HS 190-210. ECTN6 30cm deep. No dirt layer. 

Today we saw a D1 dry loose in the Ghost Couloir. It ran 200 feet. We also felt one small collapse on a south facing slope. No other avalanches observed.