Northern Madison

Storm instabilities in Middle basin

Date
Activity
Skiing

Skied into middle basin from Beehive this morning and found 8-12 inches of unconsolidated snow on top of a sun crust. While skinning back up to the Beehive/Middle ridge we remotely triggered 12 inches of storm snow on a SE facing gully from 15 ft away, the crown was ~50 ft long. ~8,200 ft. 

Winds increased throughout the morning, actively loading E aspects. 

Region
Northern Madison
Location (from list)
Middle Basin
Observer Name
J Nadison

Small skier triggered wind slab in N Madisons

NORTHERN MADISON RANGE
Northern Madison
Code
SS-ASu-R1-D1-I
Latitude
45.29520
Longitude
-111.41000
Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
1
D size
1
Bed Surface
I - Interface between new and old snow
Problem Type
Wind-Drifted Snow
Slab Thickness
8.0 inches
Vertical Fall
10ft
Slab Width
10.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Shooting cracks in Middle Basin

Middle Basin
Northern Madison
Code
Latitude
45.33740
Longitude
-111.38100
Notes

When skiing into middle basin, I stopped at the top of a convex roller and had cracks shooting out 50 feet in either direction from what seemed to be a soft slab in the new snow that slid about a foot or so. This was the most major sign of instability from the day. Lots of shooting cracks when skiing and skinning in the new snow. 

Number of slides
0
Number caught
0
Number buried
0
Problem Type
New Snow
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

New Snow Instability Beehive

Date
Activity
Skiing

About 6 inches of new snow at the trailhead around 9am. While touring to the ridge between beehive and middle basin we found strong wings actively loading east facing slopes. While moving north across the ridge, small test slopes showed cracking but no cohesive wind slabs yet. When skiing into middle basin, I stopped at the top of a convex roller and had cracks shooting out 50 feet in either direction from what seemed to be a soft slab in the new snow that slid about a foot or so. This was the most major sign of instability from the day. Lots of shooting cracks when skiing and skinning in the new snow. Throughout the day found anywhere from 8-15 inches of new snow, with the larger totals on wind loaded slopes.

Region
Northern Madison
Location (from list)
Middle Basin
Observer Name
Spencer Lipsteuer

Snowing and Blowing at Buck Ridge

Date
Activity
Snowmobiling

We rode into Buck Ridge on December 15. It was snowing and the wind was whipping up the snow that had already fallen, so visibility was limited. We rode in to the top of First and Second Yellowmule to get a closer look. The total snow depth (where it isn't stripped down by the wind) varied from 20 inches to a little over three feet. There was 6" of new snow. Similar to other areas, new snow is falling on near-surface facets. In wind-sheltered areas, there is insufficient slab to result in widespread instability, and the critical ingredient is wind-loading. We got ECTNs 5-14 on the weak layer buried 6-8" deep with no deeper failures.

I am always nervous during periods of incremental loading because we will eventually hit the breaking point. I'm avoiding wind-loaded slopes and testing the upper 2 feet of the snowpack to assess for instability before considering steeper terrain. 

Region
Northern Madison
Location (from list)
Buck Ridge
Observer Name
Dave Zinn

Skier triggered wind slab

Date
Activity
Skiing

From obs: "It slid 10' or so."

Region
Northern Madison
Observer Name
Matthew Legler