23-24

From obs: "On the west side of Henderson Moutain, we transitioned to skis and began ascending a low-angle slope toward a known avalanche path. Along the way, we experienced several collapses. Halfway up the slope, Ian noted snowballs rolling down the hill and around the corner, we could see the debris that had come from the steep terrain above. We had a clear view of this slope near the snowmobiles and it had not avalanched when we began ascending. At some point from several hundred feet away, we remotely triggered the slope.

Cooke City, 2024-01-18

From obs: "On the west side of Henderson Moutain, we transitioned to skis and began ascending a low-angle slope toward a known avalanche path. Along the way, we experienced several collapses. Halfway up the slope, Ian noted snowballs rolling down the hill and around the corner, we could see the debris that had come from the steep terrain above. We had a clear view of this slope near the snowmobiles and it had not avalanched when we began ascending. At some point from several hundred feet away, we remotely triggered the slope.

Cooke City, 2024-01-18

Lots of Action in Cooke City

Date
Activity
Skiing
Snowmobiling

North of Cooke City we observed numerous avalanches that likely happened last night or early this morning as snowfall stopped. Partly cloudy skies gave us a good view of the terrain and ridgelines. In the Fisher Creek drainage, we saw multiple natural avalanches on the east side of Henderson Moutain, including just south of Henderson Mountain off the Lulu Pass Road. At the back of the drainage, we saw another avalanche on the shoulder of Scotch Bonnet Moutain. Crown depths ranged in size but from afar seemed to be 1-2' deep. Several of these avalanches are wide and in sheltered terrain at mid-slope. 

On the other side of Henderson Moutain in the Miller Creek drainage, we observed avalanches in the gully near the Daisy Pass road. Along the east side of the Miller Ridge, we saw large natural avalanches that happened just below the ridge line. On the south side of Crown Butte, the story didn't change with two large avalanches happening mid-slope, and near the summit. Again these crowns ranged in depth from 1-2' deep and deeper on the south side of Crown Butte. 

On the west side of Henderson Moutain, we transitioned to skis and began ascending a low-angle slope toward a known avalanche path. Along the way, we experienced several collapses. Halfway up the slope, Ian noted snowballs rolling down the hill and around the corner, we could see the debris that had come from the steep terrain above. We had a clear view of this slope near the snowmobiles and it had not avalanched when we began ascending. At some point from several hundred feet away, we remotely triggered the slope. The avalanche was ~150' wide, 2' deep and ran almost to the road. Across the gully, we could see large cracks but the slope did not avalanche. Above, cracking and collapsing continued and we got a view into the upper part of the gully and saw another crown of an avalanche that likely happened at the same time as the slope below. 

Roads that were groomed last night and by 9 am had wind drifts that were a few feet in size. The snow has stopped but the wind remained blustery through the morning and into the afternoon. Getting on or under steep terrain today was certainly not in our travel plans, and it will remain that way at least through the weekend. 

 

More photos and video coming soon!

 

Region
Cooke City
Location (from list)
Henderson Mountain
Observer Name
Zach Peterson

Wolverine bowl

Date
Activity
Skiing

Wind slabs at the top of the ridge approximately 4-8 inches deep. Continued wind loading down the wolverine bowl, slabs softer the lower you go. Snowpack has about 1.5 feet of facets with a hard layer on top. New snow building up on top of that layer. Saw one small natural avalanche nearby, appeared a day old.

Region
Bridger Range
Location (from list)
Wolverine Bowl
Observer Name
Michela

Remote Trigger, Cooke City

Sheep Mountain
Cooke City
Code
SS-AMr-R0-D1-O
Latitude
45.07220
Longitude
-109.92800
Notes

We rode to the bottom of an avalanche on Sheep Mountain that had been triggered by riders from the bottom. This avalanche happened on Monday, 01/14, but by today it had been filled in by recent winds and new snow. From here we worked our way north of Round Lake and found 10"-12" of new snow (0.5" SWE), compared to the 5" of new snow near Sheep Mountain. Near the wilderness boundary, we found unstable snow and while getting a snowmobile unstuck in the flats remotely triggered a small avalanche from 100' away. We then rode to a northern aspect at 9600' and found 170 cm of snow and had poor results in our stability tests, with an ECTP 6 on buried weak layers below the last week and a half of storms. 
 

From here we rode to the top of Henderson Bench and dug on an east-facing slope at 9500'. While walking to our snowpit location we collapsed the slope and a small pocket of snow below a tree avalanched. Here we again had poor stability test results, ECTP 11, this area had previously been wind-loaded during last week's storm. Storm totals here were less than what we found north of Round Lake, with 5" of new snow at 3 pm (0.2" of SWE). 

Wind through the day was calm but is expected to increase tonight. Snow will continue tonight into tomorrow morning. Expect danger to rise as snow totals increase and wind begins transporting snow. 
 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
0
D size
1
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year