Classifying Avalanches

Avalanche Type

Classification of an avalanche based on its characteristics, such as loose snow, wet loose snow, or slab type.

Loose Snow Avalanche

An avalanche type characterized by loose, unconsolidated snow.

Trigger Mechanism

The method by which the avalanche is released, such as natural, artificial, or unknown.

Relative Scale (R)

Measures avalanche size based on factors like horizontal extent and debris volume.

R1

Very small avalanche, about 20% of the path released.

D3

Destructive potential that could bury and destroy a car or damage a few buildings.

Bed Surface

Indicates where within the snowpack the slab released during an avalanche.

Weak Layer

The layer of snow that serves as a weak point for the slab, recorded by grain type and hand hardness.

Slab Thickness

Measurement of the thickness of the slab in the avalanche.

Avalanche Terminus

Describes where the tip of the avalanche deposit stops, categorized by various data codes.

SS

Code for soft slab avalanche, usually with slabs less than 1F hardness.

U

Indicates an unknown classification for various avalanche characteristics.

SZ

Indicates the avalanche stopped in the starting zone.

c

Modifier indicating an intentional release by the trigger.

AM

Code for an avalanche triggered by a snowmobile.

MR

Indicates the avalanche stopped in the middle part of the runout.

Size Classifications

Two systems, Relative and Destructive, used to classify avalanches by size and potential impact.

I

Code representing an ice fall avalanche.

NW

An abbreviation for a northeast wind slab avalanche.