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Weather: Stability

  1. Measures of Stability
  2. Lower Atmospheric Stability (Haines) Index

Measures of Stability

Index Major Factors Primary Utility Application
Davis Stability Index Lapse rate Basic measure of stability Southeast US
Ventilation Index Mixing height and transport wind Smoke dispersion United States
Pasquill Stability Index Solar radiation, cloud cover, and surface wind speed (surface based stability) Smoke dispersion SASEM
Lavdas Atmospheric Dispersion Index Pasquill, mixing height, transport wind Smoke dispersion and fire growth potential Florida

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Lower Atmospheric Stability (Haines) Index

The Lower Atmospheric Severity Index, commonly known as the Haines Index, was developed during the 1980s as a fire weather tool to estimate the effect of atmospheric dryness and stability on the growth potential of a wildfire. The goal was to identify typical combinations of humidity and stability and contrast them with combinations of stability and humidity prevalent during problem fire outbreaks. Always reference local Climatology, see below.

Haines Index Calculation Criteria

LOW ELEVATION Stability Term (A) LOW ELEVATION Moisture Term (B)
950 – 850 mb °C
A = 1 when 3°C or less
A = 2 when 4-7°C
A = 3 when 8°C or more		 950 mb T° C – 950 DP° C
B = 1 when 5° C or less
B = 2 when 6-9° C
B = 3 when 10° C or more
MID ELEVATION Stability Term (A) MID ELEVATION Moisture Term (B)
850 – 700 mb °C
A = 1 when 5°C or less
A = 2 when 6-10°C
A = 3 when 11°C or more		 850 mb T° C – 850 DP° C
B = 1 when 5° C or less
B = 2 when 6-12° C
B = 3 when 13° C or more
HIGH ELEVATION Stability Term (A) HIGH ELEVATION Moisture Term (B)
700 – 500 mb °C
A = 1 when 17°C or less
A = 2 when 18-21°C
A = 3 when 22°C or more		 700 mb T° C – 700 DP° C
B = 1 when 14° C or less
B = 2 when 15-20° C
B = 3 when 21° C or more
Haines Index (A + B) Potential for Large Fire
2 or 3
4
5
6		 Very Low
Low
Moderate
High

U.S. Haines Elevation Classification Map

The Haines, or Lower Atmospheric Stability Index, uses different inputs based on the general classification of terrain elevation. This map displays areas of High, Mid, and Low elevation areas.

Haines Index Climatology

Modified / Reviewed:

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NWCG Latest Announcements

2025 Professional Reading Program

Date: February 18, 2025
Contact: Wildland Fire Leadership Development Program (WFLDP)

The Wildland Fire Leadership Development Program is announcing the 2025 Professional Reading list! The goal of the annual reading list is to promote the reading and discussion of the books throughout the year.

The five books chosen for this year are: Surf When You Can by Brett Crozier, Man’s Search for Meaning by Viktor E. Frankl, Elephant Company by Vicki Constantine Croke, Simply Managing by Henry Mintzberg, and Chop Wood Carry Water by Joshua Metcalf.

References:

Professional Reading Program

Task Group Volunteers Needed to Update the Property Loss or Damage Report, OF 289

Date: February 5, 2025
Contact: Julie Bennett, Incident Business Committee Chair

The Incident Business Committee (IBC) is requesting volunteers for a new task group to revise the 1981 version of the Property Loss or Damage Report, OF 289 and create an incident replacement job aid. The volunteers may be recruited from within or outside the Geographic Area Incident Business Committees.

References:

IBC Memorandum 25-02

IBC Correspondence

2025 Updates to the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1

Date: February 4, 2025
Contact: Incident and Position Standards Committee

The NWCG Incident and Position Standards Committee has updated the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1. 

These updates address changes to incident position names and requirements for qualification, training, and experience. Updates related to the implementation of Complex Incident Management (CIM) are also included.  

The NWCG Wildland Fire Position Qualification Flowchart, PMS 308 has also been updated to reflect the recent changes.

References:

NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1

NWCG Wildland Fire Position Qualification Flowchart, PMS 308

NWCG Memo: 2025-01 January 2025 Updates to the NWCG Standards for Wildland Fire Positions Qualifications, PMS 310-1

NWCG Equipment Technology Committee Releases Safety Warning: 25-001 Non-specification fire shelters

Date: January 15, 2025
Contact: Equipment Technology Committee

The Equipment Technology Committee (ETC) has released Safety Warning: 25-001 Non-specification fire shelters. Non-specification fire shelters claiming to meet Forest Service (FS) fire shelter specification 5100-606 were first found in February of 2023. As of September 2024, non-specification shelters are again being advertised and sold on the open market.

This Safety Warning outlines details and recommended procedures to purchase FS specification shelters made with materials and components that meet performance criteria and toxicity testing requirements outlined in FS Specification 5100-606. 

For additional information on identifying non-specification shelters, please view ETC Safety Warning 23-01.

References:

ETC Safety Warning 25-001: Non-specification fire shelters

NWCG Equipment Technology Committee

ETC Safety Warning 23-01