Northern Gallatin

Naturals near Flathead Pass

Flathead Pass
Bridger Range
Code
HS-N-R3-D2.5-O
Elevation
8000
Aspect
NE
Latitude
45.96840
Longitude
-111.02100
Notes

Natural avalanche crowns were seen on 2/20/2020 near Flathead Pass that appear to be from the last 2-3 days. They were fresher than crowns that were seen here on 2/9, and these slopes had not slid when the area was visited on 2/9.

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
2.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
48.0 inches
Vertical Fall
700ft
Slab Width
500.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Collapsing/Whumphing at Bear Canyon

Mt Ellis
Northern Gallatin
Code
Elevation
6800
Latitude
45.57770
Longitude
-110.95500
Notes

A group reported: "On Sunday afternoon my partner and I skinned up Bear Canyon and proceeded a half mile south along the ridge from the top of the ski hill. We were considering skiing a treed gully off the ridge down into Shoefelt gulch or skiing the East side of the ridge back into New World Gulch. As we skinned out of the trees (@ 6,800 ft) and out into the meadow above our prospective runs I caused a very audile collapse and it was obvious the wind had done a lot of work moving snow on to the east facing slope. We dug a snow pit, on a west facing slope, about 30 feet down from the ridge. The snowpack in our pit was 95CM deep, we did an extended column test and got an ECTP 13 which failed on the facets near the ground. The slab was ~70 CM. We decided to dig another pit on the east facing slope just across the ridge, making sure not to get too close to gully which looks like a slide path. My partner dug out the majority of the pit and then I joined him to perform another ECT. Just before we isolated our column my partner stepped out of the pit for a second and on he triggered another extremely audible collapse that seemed to have traveled a decent ways across the slope to the north of us, towards the gully. We got an ECTP 12 from this pit, it broke on the facets near the ground and the slab was about 80CM, the snow depth was 100CM. I thought it was interesting that we did not see much cracking while we were skinning or digging our pits, that being said the new snow from this last storm cycle was very dense and it was easy to get it to sheer when we were digging pits but we did not see it collapse. We knew going up that we probably couldn't ski any of what we checked out but had good time looking at the snowpack and skiing with the dogs back down the ridge to Bear Canyon."

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

Natural Avalanche up Moose Jaw, Storm Castle Ridge

Moose Jaw
Northern Gallatin
Code
HS-N-R3-D3-O
Elevation
9200
Aspect
N
Latitude
45.44940
Longitude
-111.07600
Notes

Very large avalanche photographed from Gallatin Gateway at the head of Little Bear Canyon. This avalanche likely occurred Saturday or Sunday during the loading event as there is snow on the debris pile. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
60.0 inches
Vertical Fall
500ft
Slab Width
1100.00ft
Weak Layer Grain type
Faceted Crystals
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Sledder triggered on Buck Ridge

Buck Ridge
Northern Madison
Code
AMu-R4-D2.5-O
Elevation
9300
Aspect
E
Latitude
45.17190
Longitude
-111.38000
Notes

"Went out on a recon to Buck Ridge today. New the dangers and avoided riding open slopes. I had been riding trees most of the day down low and moved up to about mile marker 10 later in the day. Did a side hill through open trees and stopped on top of this slope. Watched it all propagate and slide below me."

Number of slides
1
Number caught
0
Number buried
0
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
4
D size
2.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
50.0 inches
Vertical Fall
250ft
Slab Width
150.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

"I had been riding trees most of the day down low and moved up to about mile marker 10 later in the day. Did a side hill through open trees and stopped on top of this slope. Watched it all propagate and slide below me." Photo: anonymous

Northern Madison, 2020-02-17