19-20

Cooke City is getting deep! The total snow height is 315 cm. Our pit results on Scotch Bonnet were a variety of ECTNs in the upper layers of the snowpack. When placing our probe for stability tests we could feel the weak snow near the ground as our probes just dropped through the lower 60 cm of the snowpack. I am still worried about the deep layers, but it has been a while since they performed and it seems like it will take a big trigger (i.e. a cornice drop), a big storm to add weight, or some really bad luck to trigger one of the monster avalanches on the basal facets. Photo: GNFAC

Cooke City, 2020-02-16

Wolverine Bowl natural avalanche, Bridgers

Wolverine Bowl
Bridger Range
Code
SS-N-R2-D2-O
Elevation
8400
Aspect
E
Latitude
45.83010
Longitude
-110.93400
Notes

"We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide. We skinned up and down the debris pile twice while in search mode at around 12:30 but did not pick up a signal. We did not investigate above the pinch of the chute and into the upper part of the slide. The debris pile is quite deep with some damaged trees. We did 6 lines off the ramp over the weekend and did not see any other avalanche activity but obviously some significant wind loading."

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
48.0 inches
Vertical Fall
1000ft
Slab Width
30.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

"We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide.

Bridger Range, 2020-02-16

"We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide.

Bridger Range, 2020-02-16

"We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide.

Bridger Range, 2020-02-16

We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide.

Bridger Range, 2020-02-16

"We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide.

Bridger Range, 2020-02-16

Many natural avalanches on Mt Blackmore

Mt Blackmore
Northern Gallatin
Code
HS-N-R4-D3-O
Elevation
9400
Aspect Range
N-NE-NW, S-SE
Latitude
45.44670
Longitude
-111.00400
Notes

From an observation on 2/16: "My partner and I skied off the north-north east ridge of Mt Blackmore into the Fox Creek drainage and observed five recent, naturally-triggered avalanches from the recent storm. Three D1 avalanches were scattered across the bowl from the north, northeast and north-northeast aspects next to exposed rock-outcroppings but were too small to capture in a photo. A fourth, D3 R3 avalanche occurred at approximately 9200' on the north aspect that appeared to have broken right at the bedrock and slid approximately 200 vertical feet. Crown looked to be up to 6' deep and 600 feet across. The fifth, D3 R4 avalanche occurred at approximately 9400' on the north-northwest facing aspect in a narrow meadow. Crown was approximately 8' deep and 30 feet across (the width of the meadow). There was rapid wind-loading still occurring on the aspects of the two D3 avalanches covering up their slide paths and we observed significant wind-loading and cracking off the northeast ridge line."

From a separate group on 2/16: "Took a walk up near Blackmore today to take a look at a NE facing aspect. We did not ski our objective because we observed active wind loading and saw many recent avalanches.

The first picture is looking at Alex Lowe Peak from the west ridge of Elephant. There were 5 avalanches clearly visible. I highlighted the crowns/debris paths with red.

The second picture is a close up of the avalanche on the ridge between Elephant and Blackmore on a south aspect. This one was the largest and the most fresh. All avalanches appeared to be naturally triggered from wind loading.

We also saw an avalanche looking north from the NE ridge of Elephant over the east ridge of Blackmore. The avalanche was on a south/southeast facing hill and looked like it broke at the ground. It was pretty sizable. We didn't get a picture, but this looks like it would've been visible from the east ridge of Blackmore looking north."

Forecasters visited the area on 2/21/2020: Saw over 15 old avalanches. Estimate an additional 8 that the above groups did not report, so a total of 18+ in the area during the cycle.

Number of slides
15
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
40.0 inches
Vertical Fall
200ft
Slab Width
600.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year