Skip to main content

8.7 Slope Effect on ROS

When fire moves upslope, the fuel ahead of the flame front is closer to the flame than if the slope were flatter.  This set-up "preheats" the fuels. The effects of slope on fire spread become greater as the slope increases. 

graphic showing slope effects on fire

APPROXIMATING THE ROS

An easy guide for approximately the ROS due to changes in slope is as follows:
1. The first tripling of slope roughly increases the rate of fire spread by a factor of 2. 
2. The second tripling of slope increases the rate of spread by a factor of 4 to 6, depending on fuel conditions. 

The effect of an increase in slope on ROS depends both on the absolute slope as well as on the midflame wind speed. See Section 8.2 for more information on midflame and "effective" wind speeds.

Example 1 - An area of shrubs is burning at a ROS of 4 chains per hour at an 8 percent slope. The slope increases to 24 percent. What will the ROS be? 

Step 1. How much did the slope change? The slope percent increased from 8 percent to 24 percent. This change represents an increase of three times the original slope.

Step 2. How much will this slope change affect the ROS? As stated above, a tripling of slope increases the ROS by a factor of 2. 
2 × 4 chains/hr = 8 chains/hr
 

4 chains/hr × 2 = 8 ch/hr

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