Skip to main content

6MFS

6MFS Committee

All 6MFS Topics

6MFS Calendar

Aviation

Airtankers

Felling Safety

Fire Communication

Firefighter Health & First Aid

Leadership

Misc Fireline Hazards

Operational Engagement

This Day in History

Vehicles - Roads

Weather - Fire Behavior

Week of Remembrance

Replacing Haines Index and Lightning Activity Level

Background

The National Wildfire Coordinating Group (NWCG) Fire Weather Subcommittee (FWS) has recommended discontinuing the use of Haines Index (HI) and Lightning Activity Level (LAL) in fire weather forecasts and in NWCG training and curricula. A transition plan has been built to help firefighters understand what weather metrics to assess and how to brief all levels in the chain of command for the 2025 fire season.

Why are these fire weather metrics being replaced?

The HI is unsupported by research in predicting large fire growth and it is not a metric of atmospheric stability. Additionally, LAL is a duplicate of the thunderstorm coverage product that is already in the fire weather forecasts. The decision process included extensive interagency coordination and discussion as well as evaluation of peer-reviewed research.

Mixing Height

  • Mixing Height is the best current metric to replace HI.
  • Answers the question: how high in the atmosphere will rising air (fire column/smoke) ascend freely.
  • Mixing Height and Mixing Depth are interchangeable terms.
  • Mixing Height can indicate the ability of the atmosphere to support ascent of smoke and fire columns and conversely, resistance to vertical motion.
  • WHERE TO FIND: Spot Weather Forecast Discussions, Fire Weather Forecast discussions, and Fire Weather Dashboard (limited to 72 hours).
Mixing Height graph 72 hour limit.

Chance of Precipitation Crosswalk

  • Combining working in the Chance of Precipitation and Chance of Wetting Rain are the best resources (combined) to replace LAL.
  • Assessing the Potential for Lightning:
    • Are thunderstorm chances (in %) given in Sky/Weather section?
    • A higher percentage means higher odds for storms and lightning.
    • Compare to Chance of Wetting Rain (CWR). A high thunderstorm chance with low CWR may imply dry thunderstorms.
    • Remember any thunderstorm can lead to ignitions from lightning.
  • WHERE TO FIND: Chance of Precipitation and Chance of Wetting Rain from Fire Weather Planning Forecast, Spot Weather Forecast, and Fire Weather Dashboard.

References:

Category
Weather Fire Behavior

6MFS Suggestion Form


Have an idea or feedback?

Share it with the NWCG 6MFS Subcommittee
 


Follow NWCG on X and Facebook
 


 

Last Modified / Reviewed:

Print PDF

NWCG Latest Announcements

National Wildland Firefighter Day

Date: July 2, 2025
Questions?  Please contact:
National Interagency Fire Center

The National Wildfire Coordinating Group (NWCG) recognizes July 2, 2025, as National Wildland Firefighter Day (NWFFD). Established in 2022, NWFFD honors the dedication of wildland firefighters and support personnel. This day falls within the 2025 Week of Remembrance (June 30 - July 6), providing an opportunity to renew our commitment to wildland firefighter safety while remembering those who have fallen in the line of duty.

NWCG provides leadership to enable interoperable wildland fire operations among federal, state, local, Tribal, and territorial partners. NWCG standards and training establish common practices to contribute to safe, effective, and coordinated interagency wildland fire operations nationwide.

References:

Week of Remembrance

National Wildland Firefighter Day

2025 Week of Remembrance

Date: June 27, 2025
Questions?  Please contact:
6 Minutes for Safety Subcommittee

As we approach the 2025 Week of Remembrance (WOR), June 30–July 6, we dedicate this time to reflect on the past incidents from 2015 and honor the fallen through learning. Since its inception in 2014, WOR has honored wildland firefighters who made the ultimate sacrifice while encouraging critical discussions that reinforce lessons learned.

Throughout the week, we encourage thoughtful and generative conversations—whether in briefing rooms or at tailgates—that promote a culture of continuous learning and safety.

References:

2025 Week of Remembrance: Letter to Leadership

Wildland Fire Lessons Learned Center

ETC Equipment Bulletin: 25-003 Flame-Resistant Shirt Survey

Date: June 12, 2025
Questions?  Please contact:
Equipment Technology Committee

The U.S. Forest Service National Technology and Development Program (NTDP) is seeking input on the Forest Service-designed flame-resistant (FR) shirt, currently available through the National Interagency Support Cache system and FedMall.

NTDP is conducting a product review to improve future FR shirt designs. As part of this effort, a short survey is now open for federal employees who have worn any of three recent FR shirt models. Feedback will guide design improvements to better meet the needs of wildland firefighters.

To comply with the Paperwork Reduction Act, responses are limited to federal employees. The survey is open through September 12, 2025. 

References:

NWCG Alerts

ETC Equipment Bulletin: 25-003

NEW! S-130, Firefighter Training (Blended) Now Available

Date: June 10, 2025
If you have questions, please visit our FAQ page. 
If your question is not answered there, you can 
submit your question using our Contact Us form. 
 

The S-130, Firefighter Training (Blended), equips new wildland firefighters with essential skills through a mix of online learning and hands-on training. The course features a required online component and an instructor-led exercise, reinforcing online concepts with practical performance-based training.

The course builds competencies in wildland fire operations, safety, and equipment use, applicable across various operational environments. Both the online component and instructor-led field exercise must be completed to receive a certificate of completion. Students are required to finish the prerequisite S-190, Introduction to Wildland Fire Behavior, before enrolling in S-130, Firefighter Training (Blended).

References:

S-130, Firefighter Training (Blended)

S-190, Introduction to Wildland Fire Behavior

Wildland Fire Learning Portal