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PMS 437

Weather: Stability

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

Measures of Stability

IndexMajor FactorsPrimary UtilityApplication
Davis Stability IndexLapse rateBasic measure of stabilitySoutheast US
Ventilation IndexMixing height and transport windSmoke dispersionUnited States
Pasquill Stability IndexSolar radiation, cloud cover, and surface wind speed (surface based stability)Smoke dispersionSASEM
Lavdas Atmospheric Dispersion IndexPasquill, mixing height, transport windSmoke dispersion and fire growth potentialFlorida

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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)
MID ELEVATION Stability Term (A)MID ELEVATION Moisture Term (B)
HIGH ELEVATION Stability Term (A)HIGH ELEVATION Moisture Term (B)
Haines Index (A + B)Potential for Large Fire
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
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
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
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

2025 Wildland Fire EMS Awards

Date:  June 12, 2026
Questions? 
Please contact: Emergency Medical Committee

The NWCG Emergency Medical Committee (EMC) announces the recipients of the 2025 Wildland Fire Emergency Medical Service (EMS) Awards. EMC annually recognizes individuals and groups who have demonstrated outstanding actions or accomplishments that are above and beyond the expectation of one’s normal mission or job duties.

Congratulations to all the awardees and nominees. Through leadership and initiative, they have made significant contributions to the safety of the wildland fire community. These awards are well deserved.

References:

2025 Wildland Fire EMS Awards

Emergency Medical Committee

Incident Position Standards and the Next Generation Position Task Book Now Available for RAMP

Date:  June 12, 2026
Questions? 
Please contact: Airtanker Base Operations Unit

NWCG is excited to announce that Incident Position Standards and the Next Generation Position Task Book are now available for Ramp Manager (RAMP).

The Performance Support Package for this position was developed as part of the Incident Performance and Training Modernization effort. These resources support trainees, qualified personnel, and evaluators in their respective roles.

Any changes to qualification pathways will take effect with the next update of the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1, scheduled for release in January 2027.

References:

NWCG Ramp Manager Position Page

National Interagency Aviation Committee

Make an Impact: Serve the Wildland Fire Community as an IPTM SME!

Date:  June 11, 2026
Questions? 
Please contact: NWCG SME Specialist

Note: Positions with an * will last approximately 6 months.
Positions with ** will last 12 - 18 months.

NWCG is seeking experienced wildland firefighters and support personnel to serve as Subject Matter Experts (SMEs) for the Incident Performance and Training Modernization (IPTM) initiative. IPTM aims to transition NWCG’s training and qualification system to a performance-based model by updating position descriptions, Incident Position Standards, Next Generation Position Task Books (Next Gen PTBs), and training where needed.

NWCG is currently recruiting SMEs for the Fall 2026 positions listed below:

  • Equipment Manager (EQPM)*
  • Fixed Wing Parking Tender (FWPT)**
  • Mixmaster (MXMS)*
  • Public Information Officer Complex (PIOC)*
  • Retardant Crewmember (RTCM)*
  • Strike Team Leader Crew (STCR)*
  • Strike Team Leader Engine (STEN)*
  • Strike Team Leader Heavy Equipment (STEQ)*
  • Task Force Leader (TFLD)**
  • Wildland Fire Investigator (INVF)** 

Projects begin October 2026. Sign up by July 10, 2026, at the link below and review the attached document for additional details. 

References:

NWCG SME Interest Sign-up

IPTM Subject Matter Expert Duties and Expectations Document

Incident Performance and Training Modernization (IPTM)

RMC Safety Bulletin 26-001: Rhabdomyolysis in Wildland Firefighters

Date:  May 28, 2026
Questions? 
Please contact: Risk Management Committee

The Risk Management Committee (RMC) has issued Safety Bulletin 26-001: Rhabdomyolysis in Wildland Firefighters. Research from 2016 to 2025 shows that 88 cases of rhabdomyolysis (rhabdo) were reported. Analysis of reports from eSafety, the Safety Management Information System (SMIS), and the Wildland Fire Lessons Learned Center (LLC) indicates that rhabdo is common during this time of year due to Work Capacity Tests and contributing factors such as weather, hydration, nutrition, and medication or supplement use.

RMC issued this safety bulletin to raise awareness in the Wildland Fire Community, and to provide research findings and educational resources that support reducing future cases of rhabdo.

References:

NWCG Alerts

RMC Safety Bulletin 26-001: Rhabdomyolysis in Wildland Firefighters