20-21

Very Large, Natural Avalanches Divide Basin

Divide Peak
Northern Gallatin
Code
HS-R4-D3
Elevation
9800
Aspect Range
S-E
Latitude
45.39250
Longitude
-110.97600
Notes

From Obs: "I skied around the little hills in the basin south of Divide Peak today, and saw quite a bit of recent activity. The southwest corner of Divide Cirque slid on the storm slab and broke 1200-1500’ wide, an east aspect had a crown that exceeded 6’ in places, and the south side of Divide broke 2-6’ deep and ran full track. Things up high are active. I observed no collapsing or cracking, but the signs of instability were still pretty clear"

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
R size
4
D size
3
Problem Type
Persistent Weak Layer
Slab Thickness
72.0 inches
Vertical Fall
650ft
Slab Width
1200.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

From obs: "The southwest corner of the cirque slid on the storm slab and broke 1200-1500’ wide, an east aspect had a crown that exceeded 6’ in places, and the south face of Divide Peak broke 2-6’ deep and ran full track. I observed no collapsing or cracking, but the signs of instability were still pretty clear." Photo: S Reinsel

Northern Gallatin, 2021-02-15

From obs: "The southwest corner of the cirque slid on the storm slab and broke 1200-1500’ wide, an east aspect had a crown that exceeded 6’ in places, and the south side of Divide broke 2-6’ deep and ran full track. I observed no collapsing or cracking, but the signs of instability were still pretty clear." Photo: S Reinsel

Northern Gallatin, 2021-02-15

From obs: "The southwest corner of the cirque slid on the storm slab and broke 1200-1500’ wide, an east aspect had a crown that exceeded 6’ in places, and the south side of Divide broke 2-6’ deep and ran full track. I observed no collapsing or cracking, but the signs of instability were still pretty clear." Photo: S Reinsel

Northern Gallatin, 2021-02-15

Divide Basin

Date
Activity
Skiing

I skied around the little hills in the basin south of Divide Peak today, and saw quite a bit of recent activity. The southwest corner of the cirque slid on the storm slab and broke 1200-1500’ wide, an east aspect had a crown that exceeded 6’ in places, and the south side of Divide broke 2-6’ deep and ran full track. I am not sure what the bigger slides failed on, and would not feel particularly confident guessing, but things up high are active. We dug a pit on the south side of Palace Butte on Saturday and found what appeared to be a very stable snowpack, but seeing Divide slide on the same aspect is evidence that a snowpit is only part of the puzzle. I observed no collapsing or cracking, but the signs of instability were still pretty clear.

Region
Northern Gallatin
Location (from list)
Divide Peak
Observer Name
Sam Reinsel

Natural Avalanche, West Side Woody Ridge

Woody Ridge
Cooke City
Code
SS-N-R2-D2
Elevation
10000
Aspect
W
Latitude
44.97390
Longitude
-109.92400
Notes

From FB: "Winds moderate out of the west. Saw a recent wind slab natural on NW facing starting zone of tube south of Titanic. Ran into titanic approximately 500' vertical where tubes join. D2 in size."

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

From FB: "Saw recent wind slab natural on NW facing start zone of tube south of Titanic. Ran into titanic approximately 500' vertical where tubes join. D2 in size. No other signs of instabilities noted." Photo: B. Zavora

Cooke City, 2021-02-15

Just north of Hebgen Lake

Date
Activity
Skiing

Observed a dozen or more collapses while skinning up south-facing aspect between 7500 and 8300ft. Noted shallow snow depth of 2-3ft where collapses were occurring.

Region
Southern Madison
Location (from list)
Hebgen Lake
Observer Name
Zac Ferry

Ernie Miller Ridge Naturals

Ernie Miller Ridge
Southern Madison
Code
SS-N-R2-D2
Aspect
E
Latitude
44.95600
Longitude
-111.13200
Notes

Skiers at Bacon Rind saw some fresh looking avalanche activity on northern portion of Ernie Miller Ridge on Feb 14. They suspect it was from the last couple of days. 

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

Middle Basin Avalanches

Middle Basin
Northern Madison
Code
SS-N-R2-D2-I
Elevation
9500
Aspect Range
NE-SE
Latitude
45.33740
Longitude
-111.38100
Notes

From email: "Went out in Middle Basin north of Big Sky today and saw 5 separate slides, the largest about 500ft across and approximately 2ft deep. All of them were northeast to southeast aspects from about 9200 to 9800ft. The included photos aren't the best but give an idea of the slides, most are from that largest slide." Photo: B. Richards

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
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year