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PMS 437

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
Haines (Lower Atmospheric Stability) Index Lapse rate and relative humidity Large fire growth potential 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

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NWCG Latest Announcements

NWCG Training Catalog now on Wildland Fire Learning Portal

Date: April 25, 2023
Contact: NWCG Training  

The National Wildfire Coordinating Group (NWCG) has migrated the training catalog from the NWCG website to the Wildland Fire Learning Portal (WFLP) as part of our ongoing efforts to streamline processes and improve efficiency. To facilitate this transition, the training catalog remains available on www.nwcg.gov through April 2024.

Starting May 2024, the training catalog will no longer be accessible on www.nwcg.gov. However, you can still access the complete training catalog by logging in as a guest to the WFLP.

References:

Wildland Fire Learning Portal

 

NWCG Website Migration

Date: April 01, 2024
Contact: NWCG Webmaster

The National Wildfire Coordinating Group is thrilled to announce a significant upgrade to https://www.nwcg.gov, involving a comprehensive redesign of over 7,000 web pages. This enhancement is focused on improving user experience. The migration to the new NWCG website will commence on April 2, 2024, starting at noon EST and is expected to take a few hours. 

During the migration period, as the www.nwcg.gov domain-name-location updates across the Internet, you might encounter either the current or the new site depending on your location. We request your patience during this transition. If you are not redirected to the new site by April 3, 2024, we recommend clearing your browser’s cache and refreshing the page.

Please note that while navigating the revamped website, there may be instances of broken links or errors. Our dedicated web migration team has made significant efforts to minimize such issues prior to launch and will promptly address any that arise via use of analytic reports. We value your patience and understanding as we work towards enhancing your overall website experience.

WFSTAR 2023 Year in Review and 2024 Core Component Module Packages Available

Date: March 6, 2024
Contact: Joe Schindel 

The 2023 Fire Year in Review module and 2024 Core Component Module Packages for RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR) are now available on the NWCG website. The 2024 Core Component Module Package provides all content needed to deliver RT-130.

 

References:

WFSTAR 2023 Fire Year in Review module

WFSTAR 2024 Core Component Module Packages

2024 NWCG Executive Board Annual Letter

Date: March 6, 2024
Contact: NWCG

The NWCG Executive Board is privileged to share with you the 2024 NWCG Executive Board Annual Letter. As we look into the future and navigate an incredibly complex and dynamic environment, we must remain focused on our mission while actively engaging in national conversations regarding numerous wildland fire initiatives. In 2024, we prioritize building upon our successes and committing to continuous improvement. Key priorities and considerations for this year include: 

  • Determining Core Workload
  • Ensuring Incident Performance and Training Modernization (IPTM) Success
  • Improving Efficiencies
  • Firefighter Health and Wellness
  • Engagement in National Conversations

Together we will continue to make significant strides in the challenging and vital work that lies ahead. 

 

References:

2024 NWCG Executive Board Annual Letter