Observations
Avalanche Coding
Avalanche observations are coded in a standard format outlined in Snow, Weather, and Avalanches: Observation Guidelines for Avalanche Operations in the United States (American Avalanche Association, 2022). The codes below are what you’ll see on the avalanche records table. The trigger is colour-flagged by category, and every category is named in words, so nothing depends on colour alone.
Primary Trigger
Natural
- N Natural trigger
Human-triggered
- AS Skier
- AR Snowboarder
- AI Snowshoer
- AF Foot penetration
- AC Cornice fall triggered by human or explosive action
- AM Snowmobile
- AN Motorized snowbike
- AK Snowcat
- AV Vehicle
- AW Wildlife
- AU Unknown artificial trigger
- A Artificial
Explosive
- AA Artillery
- AE An explosive thrown or placed on or under the snow surface by hand
- AL Avalauncher
- AB An explosive detonated above the snow surface (airblast)
- AX Gas exploder
- AH Explosive placed vis helicopter
- AP Pre-placed, remotely detonated explosive charge
- AO Unclassified artificial trigger
Unknown
- U Unknown
Secondary Trigger
A second code records how the avalanche was released.
- u An unintentional release
- c An intentional release by the indicated trigger
- r A remote avalanche released by the indicated trigger
- y An avalanche released in sympathy with another avalanche
- U Unknown
Aspect
The compass direction the avalanche’s start zone faces.
- N North
- NE Northeast
- E East
- SE Southeast
- S South
- SW Southwest
- W West
- NW Northwest
- U Unknown
Elevation
The elevation band of the start zone, relative to treeline.
- All All
- >TL Above Treeline
- TL At Treeline
- <TL Below Treeline
- U Unknown