Pro Field Report
Basic Information
Observation Details
Observation Date:
March 31, 2023Submitted:
March 31, 2023Observer:
SAC - Jon Preuss (off duty)Zone or Region:
Soldier and Wood River Valley MtnsLocation:
Morgan Ridge (SW-NW-N; 6000-8500')Signs of Unstable Snow
Recent Avalanches?
YesCracking?
None ExperiencedCollapsing?
IsolatedBottom Line
Natural avalanches were occurring on sunny slopes with weak layers of crusts buried in the upper snowpack. The sun helped trigger these slides in the afternoon, despite winds coming from the south.
Advanced Information
Weather Summary
Cloud Cover:
Mostly CloudyWind:
Light , SWA couple of squalls passed over with no accumulation. The wind picked up in the afternoon with light drifting snow over my skin track. Cloud over was broken through much of the afternoon with strong solar input.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Photos | Details |
|---|---|---|---|---|---|---|---|---|---|
| 3 |
Mar 31, 2023 (Exact) |
Johnstone Peak W 9400ft |
D2 | SS-Soft Slab | N-Natural |
|
Report |
Snowpack Observations
Lower elevation NW slopes had 17 cm over a melt-freeze. Two more crust/facet layers were below the new/old layer. On an SW slope below 7500, ~10 cm of moist snow was on top of a thick melt-freeze crust.
A north-facing snow pit at 8,200' had no weak layers failing with propagating results in the upper snowpack. The new/old layer was down 15 cm, another layer down 26 cm, and one at 40cm. Small column tests had resistant planar results with 2-12 hits. ECTX results on the 2/18 layer, which was down 110 cm.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
|
|
Comments: Based on the avalanche activity near Johnstone Peak, which falls on the line between the WRV and Eastern Mtn zones. |
The weak layers on the shady slopes seem to be more stubborn than the opposite side of the compass. It likely takes a wind-affected slope to get them to be more reactive.