Acronyms in the MIN

Some Mountain Information Network (MIN) reports contain acronyms to communicate snowpack test results and other information. Below is a list of the most used acronyms and their meaning. This list is meant to help you better understand these MIN reports. It is not meant as an instruction on how to interpret the results.

Snowpack Tests

The most common terms you’ll see in the MIN refer to snowpack tests.

Snowpack tests involve digging a large square hole in the snow (aka a pit), then isolating a column of snow to test the reactivity of weak layers within it. Watch this video by forecaster Mike Conlan for instructions on a variety of snowpack tests:

Snowpack tests are indicative of a specific location only. The snowpack can vary tremendously across different elevations, aspects, and even the same slope. If you see test results in a MIN report, consider them as one piece of a much larger avalanche conditions puzzle.

Compression Test

We often see compression test results in MIN reports, as it is the easiest snowpack test to perform. This test is used to identify weak layers in the snowpack and assess their strength. Conducting a CT involves isolating a 30x30 cm column, placing the flat part of the shovel on top of the column, and applying a series of taps to the shovel blade with increasing strength.

There are three topics of interest: the number of taps required to cause a fracture; the character of the fracture; and the depth of the layer that fractured.

Results are ususally recorded in this style: CTM15 down 32, SP.

In this example:

  • CTM15 means compression test moderate that took 15 taps to trigger a fracture
  • Down 32 is the depth of the weak layer that failed
  • SP indicates the fracture character.

Acronym

Result

# taps

Notes

CTV

Very easy

0

Layer fails while isolating column

CTE

Easy

1-10

Tap column from wrist

CTM

Moderate

11-20

Tap column from elbow

CTH

Hard

21-30

Tap column from shoulder

CTN

None

>30

No fracture occurred

These are the acronyms relating to compression test results:

Fracture Character

Fracture character is a description of how the weak layer responds to the load of the compression test. There are five types of fracture character broken into three major classes: sudden, resistant, or break. Sudden failures indicate a greater likelihood of slab avalanches than resistant failures and breaks. Watch this video by Dr. Bruce Jamieson, a leading avalanche researcher, to learn more about fracture character.

Acronym

Type

Major class

Description

SP

Sudden planar

Sudden

A thin planar fracture suddenly crosses the column in one loading step AND the block slides easily on the weak layer.

SC

Sudden compression

Sudden

The fracture crosses the column with a single loading step and is associated with a noticeable collapse of the weak layer.

RP

Resistant planar

Resistant

A planar result that requires more than one tap to slide, or where the block does not slide easily.

PC

Progressive compression

Resistant

Occurs when a weak layer is squished down over a series of taps.

BRK

Non-planar break

Break

A non-planar, irregular fracture

These are the acronyms relating to fracture character:

Extended Column Test

We also see these extended column test (ECT) results in the MIN. The ECT assesses both initiation (how much force it takes a weak layer to fail) and propagation (how far the failure will spread across the column, and, possibly, across the slope). The ECT involves isolating a column 90cm x 30cm, placing the shovel blade on top of the column at one end, and applying the same series of taps as the compression test. Results are recorded in this style:

  • ECTP15 means a fracture propagated across the entire column on the 15th tap (from the elbow).
  • ECTN25 would mean a fracture occurred on the 25th tap (from the shoulder), but it did not propagate.

Acronym

Definition

ECTPV

Fracture crosses the entire column during isolation.

ECTP##

Fracture crosses the entire column on the ## tap, or a fracture is observed on the ## tap and crosses the column on the next one.

ECTN##

Fracture observed on the ## tap but does not propagate across the column on either that tap or the next one.

ECTX

No fracture observed during the test.

These are acronyms relating to ECT results: 

Snow Hardness

Snow hardness, or density, is a common measurement taken during a snow profile and indicates the relative strength of various layers throughout the snowpack. The person conducting the snow profile will first identify the separate layers, and then assess each layer’s hardness using their hand, a pencil, or a knife.

Acronym

Test

Estimated Result

F

Fist in glove

Very light snow (powder)

4F

Four fingers in glove

Light snow

1F

One finger in glove

Medium-density snow

Pencil

Blunt end of a pencil

Hard snow

K

Knife

Very hard snow

I

Too hard to insert a knife

Ice

This is how snow hardness is recorded:

Other Acronyms

Acronym

Definition

SH

Surface hoar

FC

Facets

MFCr

Melt-freeze crust

DH

Depth hoar

HS

Total height of the snowpack

HST

Height of storm snow (amount that's fallen in the latest storm)

Na

Natural avalanche

Sa

Skier-triggered avalanche

Alp

Alpine elevation

TL

Treeline elevation

BTL

Below treeline elevation

Here are some other acronyms you may encounter in the MIN. Click on the links (note: will link to glossary) to learn more about them.

We hope this helps you understand the Mountain Information Network better. If you have any questions, please email info@avalanche.ca.