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Extreme Fire Behavior – I

 

Fire managers make decisions throughout the day on how to suppress fires and best use resources while protecting life and property. This Standard Firefighting Order depicts a firefighter observing increased fire behavior during a time of day when temperatures are high and relative humidity is low.

3. Base all actions on current and expected behavior of the fire. A firefighter looks at his watch, which reads 2 PM, while a fire actively grows in steep terrain and heavy timber.

3. Base all actions on current and expected behavior of the fire.

Read about all 10 Standard Firefighting Orders.

Changes in fire behavior have always been present in cases of shelter deployment. It is critical for firefighters to maintain situation awareness of live and dead fuel moisture conditions, as well as predicted and current weather conditions. As fire behavior moves from mild to moderate to extreme, it is critical to act decisively regarding the changing situation.

Discuss the following indicators of extreme fire behavior:

  • Relative humidity less than 15%.
  • 1-hour fuel moisture less than 5%.
  • Transition from surface to crown fire.
  • Smoldering fires that exist in the early part of the day are beginning to burn very actively as the day progresses.
  • Approaching thunderheads with dark clouds beneath.
  • Presence of dust devils indicating atmospheric instability.
  • Increased spotting.
  • Sudden calm.
  • High clouds moving fast in a direction that is different from surface wind.
  • Predicted Haines Index of 5 and 6 in those areas where this level is a good indicator of atmospheric instability.
  • Fire whirls.

Image of a fire whirl twisting up from a forest fire.

 

Category
Weather Fire Behavior

Last Modified / Reviewed:


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Updated NWCG Guide for Wildland Fire Modules, PMS 431

Date: May 14, 2025
Questions?  Please contact:
Fire Use Subcommittee

The updated NWCG Guide for Wildland Fire Modules, PMS 431 serves as a supplemental resource for wildland fire module operations, providing information frequently used in the field.

PMS 431 defines the organizational structure, staffing, and qualifications for Type 1 and Type 2 Wildland Fire Modules, outlining their roles in wildland fire suppression, prescribed fire, and resource management. The NWCG Guide for Wildland Fire Modules, PMS 431, should be used in conjunction with the NWCG Standards for Wildland Fire Module Operations, PMS 430.

References:

NWCG Guide for Wildland Fire Modules, PMS 431

NWCG Standards for Wildland Fire Module Operations, PMS 430

Updated NWCG Standards for Wildland Fire Resource Typing, PMS 200 Now Includes Off-Highway Vehicle Typing Standards

Date: May 13, 2025
Questions?  Please contact:
Mobile Fire Equipment Subcommittee 

The NWCG Standards for Wildland Fire Resource Typing, PMS 200 has been updated to include newly developed Off-Highway Vehicle (OHV) typing standards. These standards organize OHV information into logical categories and outline key safety requirements for occupants.

NWCG Standards for Wildland Fire Resource Typing, PMS 200 establishes minimum typing standards for aircraft, crews, and equipment used in national mobilization to wildland fire incidents. Typing designations are assigned based on measurable capability and performance criteria.

References:

NWCG Standards for Wildland Fire Resource Typing, PMS 200

NEW! S-204, Interpersonal and Critical Thinking Skills for Safety Officers Now Available

Date: May 12, 2025
Questions?  Please contact:
Risk Management Committee

The S-204, Interpersonal and Critical Thinking Skills for Safety Officers self-directed online course is now available! Developed through the Incident Performance and Training Modernization (IPTM) effort, this training supports individuals working towards Safety Officer, Field (SOFF) incident qualifications.

S-204, Interpersonal and Critical Thinking Skills for Safety Officers focuses on facilitating hazard mitigation conversations and building trust to influence safety-related decisions. Individuals can self-enroll through the Wildland Fire Learning Portal (WFLP).

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

References:

S-204, Interpersonal and Critical Thinking Skills for Safety Officers 

NWCG Safety Officer, Field (SOFF) Position Page

Wildland Fire Learning Portal

Great Basin Cache Upgrading to New Inventory System

Date: May 7, 2025
Questions?  Please contact:
Great Basin Cache
Phone: (208) 387-5104
Fax: (208) 387-5573

The Great Basin Cache (GBK) is transitioning to a new inventory system to better serve the wildland fire community. During this upgrade, GBK will be unable to process standard orders from Part 1: Fire Supplies and Equipment and Part 2: Publications between May 8-20, 2025, with exceptions made for emergency fire orders. Orders will be accepted through close of business May 7.

To browse the latest available items, please refer to the National Fire Equipment System (NFES) catalogs. 

References:

NWCG NFES Catalog-Part 1: Fire Supplies and Equipment, PMS 449-1

NWCG NFES Catalog-Part 2: Publications, PMS 449-2