Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
December 16, 2019
Submitted:
December 17, 2019
Observer:
SAC - VandenBos (off duty)
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
Morgan Ridge -> Johnstone

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
Isolated
Isolated cracking and collapsing on recent wind slabs where deposited on stiff surfaces.

Snow Stability

Stability Rating: 
Good
Confidence in Rating: 
Moderate
Stability Trend: 
Steady

Bottom Line

Inadequate amount of snow for widespread problems, did not have to worry about avalanche problems until I got into upper elevation, shaded terrain. Terrain use was driven by presence/absence of snow.

Media/Attachments

Snow coverage on Morgan Ridge. Photo looking W at 8,200'

Advanced Information

Weather Summary

Cloud Cover:
Clear
Wind:
Light , NW

Clear and cold all day - surfaces didn't seem to get burned but the only due solar slopes I traveled on where quite low in angle. I suspect 35-40 degree S-SW took a crust. Calm down low, light to low end of mod NW winds up high.

Snowpack Observations

Thin, faceted snowpack in the WRV, HS=0-40cm. Where snow remains on solars the snow was cooked on and supportable. Sheltered, shaded aspects have faceted heavily, could have a budding persistent issue in upper elevation northerly paths from facets alone. Found SH at 12/7 interface (10-20cm down), remarkably similar in appearance to everything I've found north of here. Standing 5-15mm xtals with plenty of open space above. Not enough of a slab to be a widespread problem, but I'd expect it could be an isolated issue in heavily wind loaded areas. Definitely something to keep in mind as we continue to build the slab, we're far from over the hump on this one.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 5-15cm
Comments: Small, isolated wind slabs in upper elevation WRV terrain were the only problem I directly encountered. Thin slabs (4F-P hardness) sitting on stiff surfaces were shooting cracks up to 1.5m long. Unreactive slabs existed at lower elevations, but I had to get up to ~7500 to 8000' before they would do much of anything.
Persistent Slab
Layer Depth/Date: 12/7, down 10-20cm
Comments: Found SH at 12/7 interface, remarkably similar in appearance to everything I've found north of here. Standing 5-15mm xtals with plenty of open space above. Not enough of a slab to be a widespread problem, but I'd expect it could be an issue in heavily wind loaded areas. Definitely something to keep in mind as we continue to build the slab.

Terrain Use

Inadequate amount of snow for widespread problems, did not have to worry about avalanche problems until I got into upper elevation, shaded terrain. Terrain use was driven by presence/absence of snow.