19-20

Snowmobiler triggered avalanches in Portal Ck, N. Gallatin

Portal Creek
Northern Gallatin
Code
SS-AMu-R2-D1-I
Latitude
45.28900
Longitude
-111.14100
Notes

A snowmobiler found very touchy conditions in Portal Creek. The new snow easily avalanched on road cuts so they went home.

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
1
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Snowmobile Triggered Avalanches, McAtee Basin

McAtee Basin
Northern Madison
Code
SS-AMu-R2-D2-O
Elevation
8900
Aspect
SW
Latitude
45.17710
Longitude
-111.43500
Notes

We saw a group of six snowmobilers who said they triggered these slides in McAtee Basin on the left side of the meadow on Saturday, Feb 8. I didn't see tracks up on the hill or sidehill tracks so they may have triggered the slope from the flats below. The debris runs all the way to the bottom of the hill. 

Number of slides
3
Number caught
0
Number buried
0
Number killed
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
36.0 inches
Vertical Fall
250ft
Slab Width
100.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

We saw a group of six snowmobilers who said they triggered these slides in McAtee Basin on the left side of the meadow on Saturday, Feb 8. I didn't see tracks up on the hill or sidehill tracks so they may have triggered the slope from the flats below. The debris runs all the way to bottom of the hill. Photo: K Peaslee

Northern Madison, 2020-02-08

We saw a group of six snowmobilers who said they triggered these slides in McAtee Basin on the left side of the meadow on Saturday, Feb 8. I didn't see tracks up on the hill or sidehill tracks so they may have triggered the slope from the flats below. The debris runs all the way to bottom of the hill. Photo: K Peaslee

Northern Madison, 2020-02-08

We saw a group of six snowmobilers who said they triggered these slides in McAtee Basin on the left side of the meadow on Saturday, Feb 8. I didn't see tracks up on the hill or sidehill tracks so they may have triggered the slope from the flats below. The debris runs all the way to bottom of the hill. Photo: K Peaslee

Northern Madison, 2020-02-08

Natural Deep Slab Saddle Peak

Saddle Peak
Bridger Range
Code
HS-N-R3-D3.5-O
Elevation
8900
Aspect
NE
Latitude
45.79430
Longitude
-110.93600
Notes

A natural 4-8' deep slab avalanche broke on Saddle Peak within the last couple days (2/6 or 2/7) during the current storm. The mountains received 3-5 feet of snow equal to 3-5" of SWE over the last week with more snow in the forecast.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
3.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
60.0 inches
Vertical Fall
2500ft
Slab Width
1700.00ft
Weak Layer Grain type
Faceted Crystals
Slab Layer Grain Type
Wind packed
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year