23-24

Natural avalanche on East Henderson

Date
Activity
Skiing

Natural avalanche on East Side of Henderson Mtn. seen late on 2/7/24. South of the two that Doug saw last week, along the ridge. Could have happened yesterday or last night. I didn’t see it yesterday when riding up and down Fisher creek, but visibility was mediocre. The debris and bed had at least some new snow on it.

Also had a large rumbling collapse near 10,000’ west facing when following one skiers old skin track. And had a few large collapses on south facing slopes between 8,000-9000’. 

Region
Cooke City
Location (from list)
Henderson Mountain
Observer Name
Alex Marienthal

Large Avalanche Tepee Basin

Tepee Basin
Southern Madison
Code
AMr-R4-D3-O
Elevation
9500
Aspect
NE
Latitude
44.90410
Longitude
-111.18500
Notes

From FB Messenger and phone conversation: A group (group 1) of sledders in the meadows of Tepee Basin witnessed an avalanche that failed an estimated 4 feet deep and up to one mile wide of the NE-facing wall that makes up the perimeter of Tepee Basin. They described the avalanche as breaking across the entire face, which, measured on Google Earth, is over a mile wide. 

A second group (group 2) was riding higher in the meadow. We suspect that group remotely triggered the avalanche. 

Group 1 confirmed that group 2 was clear and they got out their beacons to confirm no one else was captured. 

From FB Messenger (second group): "The whole skyline ridge went off this afternoon on the Tepee side. We may have triggered it with our tree riding below, but the whole thing let go about a mile wide."

Video overview: O. El-Zaru

Number of slides
1
Number caught
0
Number buried
0
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
48.0 inches
Vertical Fall
600ft
Slab Width
4000.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Collapsing Henderson Mt., Cooke City

Henderson Mountain
Cooke City
Code
Latitude
45.05240
Longitude
-109.94500
Notes

From email: "Breaking trail, we experienced at least 20 collapses, several of which were large enough to knock snow off the trees around us. Above 9200’ where the snowpack started to deepen, we did not get any collapses or cracking. "

Number of slides
0
Number caught
0
Number buried
0
Problem Type
Persistent Weak Layer
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Henderson Mountain Observations

Date
Activity
Skiing

From email: "My friend and I toured in Cooke City today. We skied the low angle glades on the South side of Henderson Mountain. Breaking trail, we experienced at least 20 collapses, several of which were large enough to knock snow off the trees around us. Above 9200’ where the snowpack started to deepen, we did not get any collapses or cracking. We dug a quick pit at 9750’ on a SSE aspect. The site we dug on had been wind loaded substantially before the high pressure cycle last week. Skies were mostly cloudy with the sun poking out occasionally, light winds out of the west. Our ECT did not have propagation, but the results from our CT test were poor. Given the sketchy conditions, we stuck to low angle terrain." 

Region
Cooke City
Location (from list)
Henderson Mountain
Observer Name
Nicholas Salsburg

New Snow in Taylor Fork

Date
Activity
Snowmobiling

We rode into Taylor Fork today 02/07/2024. We found 12" of new snow that has fallen over the last few days. This new snow fell onto a very weak snowpack and our stability tests yielded poor results, ECTP 14 on a south-facing slope at 9200'. Southern aspects have a stout 2" crust that formed from last week's warm temperatures, over weak faceted snow. This is where we saw failure in our stability tests. 

With poor visibility, we were not able to see any recent avalanche activity. However, we know the recipe is there. A uniformly weak snowpack has received a large amount of snow pushing it to the edge. Getting on or below terrain steeper than 30 degrees is not recommended. 

Low clouds moved in by early afternoon and the wind was steady and moderate from the southwest. No new snow fell while we rode today. 

Region
Southern Madison
Location (from list)
Taylor Fork
Observer Name
Zach Peterson

Fractured slope in hyalite

Date
Activity
Skiing

Skied a northeast face that was around 35-40 degrees at around 9000 ft. Entire slope fractured on second ski cut but did not slide. A dusting of new snow, with a good bit of powder on the ground. 

Region
Northern Gallatin
Location (from list)
Hyalite - main fork
Observer Name
Jay Alford

Poor Stability on ECT in Beehive Basin

Date
Activity
Skiing

Persistent Problem visible

isolated shooting cracks and some roller balls observed 

Region
Northern Madison
Location (from list)
Beehive Basin
Observer Name
John Emmett, Jamie McCready, and Justin Weissman