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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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2024 Week of Remembrance

Date: June 27, 2024
Contact: 6 Minutes for Safety Subcommittee 

As we approach the 2024 Week of Remembrance (WOR), June 30 to July 6, we dedicate this time to thoughtfully reviewing and recognizing the events of the 2018 Mendocino Complex. As such, this year’s theme of “Learning From the Mendocino Complex” embodies a longstanding hallmark of WOR, honoring through learning.

Throughout the week, our energy will be directed toward fostering generative conversations in briefing rooms and at tailgates.

References:

6 Minutes for Safety - 2024 Week of Remembrance

Wildland Fire Lessons Learned Center

Updated NWCG Wildland Fire Risk and Complexity Assessment, PMS 236

Date: June 24, 2024
Contact: Incident and Position Standards Committee 

The June 2024 update of the NWCG Wildland Fire Risk and Complexity Assessment, PMS 236, is now available to meet the current needs for incident management typing.

The NWCG Wildland Fire Risk and Complexity Assessment should be used to evaluate firefighter safety issues, assess risk, and identify the appropriate incident management organization based on incident complexity. Assessing risk, determining incident complexity, and identifying an appropriate incident management organization is a subjective process based on examining a combination of indicators or factors, which can change over time.

References:

NWCG Wildland Fire Risk and Complexity Assessment, PMS 236

Operations Branch Director (OPBD) Next Gen PTB Available

Date: June 10, 2024
Contact: NWCG Feedback 

The NWCG Position Task Book for Operations Branch Director (OPBD), PMS 311-109 is now available for use within the OPBD position qualification pathway. As part of the transition to Complex Incident Management (CIM), the OPBD Next Gen PTB was developed and the position qualification pathway updated.

More information about the Next Gen PTB format can be found on the NWCG Position Task Book webpage.

References:

Operations Branch Director Position Page

Operations Branch Director Next Gen PTB

NWCG Position Task Books

Updated NWCG Standards for Interagency Incident Business Management, PMS 902

Date: June 5, 2024
Contact: NWCG Incident Business Committee 

The 2024 revision of the NWCG Standards for Interagency Incident Business Management, PMS 902 is now available. The uniform application of interagency incident business management standards is critical to interagency fire operations. PMS 902 assists NWCG agencies in constructively working together to provide effective execution of each agency's incident business management program.

References:

PMS 902