23-24

Natural Avalanches at Lionhead

Lionhead Ridge
Lionhead Range
Code
N-R2-D2-O
Elevation
9000
Aspect Range
N, S, E, W
Latitude
44.71450
Longitude
-111.31800
Notes

On 2/16/24 GNFAC forecasters 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, including during an avalanche warning on 2/15, 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 at least 2' deep and 100' wide. Near ridgelines there were many avalanches, harder slabs, at least 2' deep breaking hundreds of feet wide.

Number of slides
4
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
24.0 inches
Slab Width
150.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

GNFAC Avalanche Forecast for Sat Feb 17, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Don’t let the beautiful weather today fool you, avalanche conditions remain quite dangerous. Avalanches will be easily triggered if you get on, or even near, any steep slope.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Yesterday, there were many skier and rider triggered avalanches across the advisory area. Large avalanches were triggered on Henderson Mountain and Scotch Bonnet, near Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30787"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30780"><span><span><span><strong><span…;). The larger of these slides broke 800 ft wide and 3-4 ft deep (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/scotch-bonnet-slide"><span><span>…;). Riders in Portal Creek remotely triggered four avalanches from up to 900 ft away (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30799"><span><span><span><strong><span…;). And Alex and I saw a slide near Lionhead that was remotely triggered during the day yesterday from around 150 ft away by a group of riders in a flat meadow on the far side of a band of trees (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30792"><span><span><span><strong><span…;). The remarkably weak layers in the snowpack will take a long time to heal. Loading has just stopped and this process has barely begun. Expect to trigger more of these deep, wide, slides today. Because so many avalanches are being triggered from far away, make sure to give steep slopes wide berths if you’re crossing beneath them.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Dave dug a snowpit in Bear Basin on Thursday and got unremarkable test results but advised ignoring them because of the big picture signs of instability (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=5KoxeBr3WRI"><span><span><span><strong>…;). That night, a natural avalanche broke only a couple hundred feet away from his snowpit (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30796"><span><span><span><strong><span…;). This is a great example of why we should all follow his advice and not over complicate our decision making right now. Simply plan to avoid riding on, or beneath, all slopes steeper than 30 degrees regardless of what signs of instability you do or don’t see while you’re travelling through the mountains.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Slopes where winds have blown recent snow into thicker drifts may be even touchier than others, but don’t worry about trying to identify these slopes, because human triggered avalanches are likely on all slopes today whether wind-loaded or not.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is CONSIDERABLE today.&nbsp;</span></span></span></span></span></span></p>

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4 remote triggered avalanches in Portal Creek

Portal Creek
Northern Gallatin
Code
SS-AMr
Latitude
45.28900
Longitude
-111.14100
Notes

From facebook on 2/16/24: "Rode up Portal creek today ... We triggered 4 avalanches with the farthest one being 300 yards away. The one in the photo was the scariest one. We were playing below the windy pass hillclimb and the chute next to it let go. We had a sledder almost get caught in it, but thankfully everyone was ok. It's scary out there!"

Number of slides
4
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
Problem Type
Persistent Weak Layer
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

From facebook: "Rode up Portal creek today... We triggered 4 avalanches with the farthest one being 300 yards away. The one in the photo was the scariest one. We were playing below the windy pass hillclimb and the chute next to it let go. We had a sledder almost get caught in it, but thankfully everyone was ok. It's scary out there!"

Northern Gallatin, 2024-02-17

Triggered 4 avalanches up Portal Creek

Date
Activity
Snowmobiling

From facebook: "Rode up Portal creek today. Meadows were killer! We had first tracks all the way back to Windy Pass. We triggered 4 avalanches with the farthest one being 300 yards away. The one in the photo was the scariest one. We were playing below the windy pass hillclimb and the chute next to it let go. We had a sledder almost get caught in it, but thankfully everyone was ok. It's scary out there!"

Region
Northern Gallatin
Location (from list)
Portal Creek

Natural avalanche in Bear Basin

Bear Basin
Northern Madison
Code
SS-N-R2-D2
Latitude
45.34530
Longitude
-111.37500
Notes

From instagram on 2/16/24: "Just getting to the ridge by prayer flags in Beehive basin. 100 maybe 200 yards wide. Cracked all the way around the corner almost to a couple old tracks. Seemed to be a natural from last night or this morning."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From instagram on 2/16/24: "Just getting to the ridge by prayer flags in Beehive basin. 100 maybe 200 yards wide. Cracked all the way around the corner almost to a couple old tracks. Seemed to be a natural from last night or this morning."

Photo: S. Knowles

Northern Madison, 2024-02-16

Natural avalanche near Prayer Flags

Date
Activity
Skiing

From instagram: "Just getting to the ridge by prayer flags in Beehive basin. 100 maybe 200 yards wide. Cracked all the way around the corner almost to a couple old tracks. Seemed to be a natural from last night or this morning.

We saw another big natural avalanche further up the ridge into middle that was a few days old. Propagated across multiple gullies. Crown was 2-3 ft."

 

 

Region
Northern Madison
Location (from list)
Beehive Basin
Observer Name
Shane Knowles