23-24

Remotely triggered avalanche Lionhead

Lionhead Ridge
Lionhead Range
Code
HS-AMr-R3-D2-O
Elevation
8900
Aspect
N
Latitude
44.71450
Longitude
-111.31800
Notes

On 2/16/24 we saw a fresh avalanche in Watkins Creek that we think was triggered remotely during the day by a group riding in a flat meadow above, where we saw their tracks at least 150 feet away (photo). This slide was 2-3' deep and 100-150' feet wide, breaking on old sugary snow. HS-R3/4-D2-O. We rode along the flat terrain above the avalanche and could feel our sled tracks punch through the supportable slab into weak snow at the bottom of the snowpack.

We felt a couple collapses while sitting on our sleds, and saw a couple long shooting cracks while riding. We dug a snowpit in Targhee creek on a northwest facing slope at 9,435'. We had an ECTP27 below a 2.5' deep slab, sitting on 1.5' of weak sugary snow.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
32.0 inches
Vertical Fall
200ft
Slab Width
150.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

We saw a fresh avalanche in Watkins Creek that we think was triggered remotely during the day on 2/16 by a group that was riding in a flat meadow above, where we saw their tracks at least 150 feet away (photo). This slide was 2-3' deep and 100-150' feet wide, breaking on old sugary snow. HS-R3-D2-O. Photo: GNFAC

Lionhead Range, 2024-02-16

Fresh avalanche and many recent avalanches

Date
Activity
Snowmobiling

We rode up Denny Creek below Lionhead Ridge, then around to the north, through Watkins Creek and into the top of Targhee Creek. We saw a lot of old and recent avalanches that happened at various times over the last week, and in a wide variety of terrain. On lower elevation, generally non-wind-loaded terrain in the trees we saw at least 4 avalanches that were 2'+ deep and 100'+ wide. Near ridgelines there were many avalanches, harder slabs, 2'+ deep breaking hundreds of feet wide.

On our way out we saw a fresh avalanche in Watkins Creek that we think was triggered remotely during the day by a group that was riding in a flat meadow above, where we saw their tracks at least 150 feet away (photo). This slide was 2-3' deep and 100-150' feet wide, breaking on old sugary snow. HS-R3/4-D2-O. We rode along the flat terrain above the avalanche and could feel our sled tracks punch through the supportable slab into weak snow at the bottom of the snowpack.

We felt a couple collapses while sitting on our sleds, and saw a couple long shooting cracks while riding. We dug a snowpit in Targhee creek on a northwest facing slope at 9,435'. We had an ECTP27 below a 2.5' deep slab, sitting on 1.5' of weak sugary snow.

Skies were mostly sunny with a light breeze out of the north.

Region
Lionhead Range
Location (from list)
Lionhead Ridge
Observer Name
Alex Marienthal

Avalanche Sheep Mountain

Date
Activity
Snowmobiling

From email: "Was in round lake was visiting with a guy in the warm up shack.  He said he caused a decent size avalanche on the sheep mountain side. 

It was roughly 100 feet wide, he was hit by the avalanche but didn’t get buried."

Region
Cooke City
Location (from list)
Sheep Mountain

Rider Triggered Avalanche Henderson Mountain

Henderson Mountain
Cooke City
Code
SS-AM-R2-D2-O
Elevation
10000
Aspect
E
Latitude
45.05240
Longitude
-109.94500
Notes

Snowmobilers observed an avalanche on the east side of Henderson Mountain that appeared to be rider triggered. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Slab Width
200.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Avalanche Chimney Rock, Cooke City

Daisy Pass
Cooke City
Code
SS-N-R2-D2-O
Elevation
9800
Aspect
N
Latitude
45.04970
Longitude
-109.96400
Notes

A natural avalanche happened early in the morning on the north side of Chimney Rock near Daisy Pass. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Vertical Fall
500ft
Slab Width
400.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year