Hot-Dry-Windy Fire Weather Index

Research Issue

Fire weather indices are commonly used by fire weather forecasters to predict when weather conditions will make a wildland fire difficult to manage. Complex interactions between fire, fuels, topography, and weather make accurate predictions extremely difficult. In order to simplify the problem, we have defined a new fire weather index called the Hot-Dry-Windy Index (HDW) that can be used to assess the potential for routinely forecasted, large-scale atmospheric conditions to affect a fire. Our Research HDW is designed to show when meteorological conditions both at the Earth’s surface and in a 500-m layer just above the surface can affect a fire. Our research suggests that HDW can identify days on which large-scale weather patterns contribute to especially dangerous fire behavior. An analysis of four historical fires shows that HDW out-performed the Haines Index, the most widely used fire weather index in the United States, for those four fires. Additional research is underway to examine the performance of HDW on a much larger number of fires and to investigate whether HDW can be used to anticipate other weather-related impacts that could affect fire behavior and management decisions.

Our Research

[graph] The Pagami Creek Fire occurred in the Boundary Waters Canoe Area Wilderness of the Superior National Forest in northern Minnesota. Most of the area burned on 12 September, and Sexton et al. (2012) identifies 12 September as the date on which the most “active fire behavior” was reported. The figure shows a time series of HDW from 29 August through 26 September for the CFSR grid point closest to the fire location. The time series indicates that HDW spiked on 12 September, so a daily trace of HDW identified the date on which the most active fire behavior occurred. This indicates that synoptic and meso-alpha scale weather was at least partially responsible for the active fire behavior observed on 12 September.HDW is designed to show when meteorological conditions both at the Earth’s surface and in a 500-m layer just above the surface can affect a fire. Our research suggests that HDW can identify days on which large-scale weather patterns contribute to especially dangerous fire behavior. An analysis of four historical fires shows that HDW out-performed the Haines Index, the most widely used fire weather index in the United States, for those four fires. Additional research is underway to examine the performance of HDW on a much larger number of fires and to investigate whether HDW can be used to anticipate other weather-related impacts that could affect fire behavior and management decisions.

Expected Outcomes

HDW research is expected to produce a tool that can be used by fire weather forecasters and fire managers to help inform their decision-making when managing prescribed fires and wildfires. This tool in its current form should be produced operationally using one or more weather forecast models. Additional analyses are underway to assess the climatological variability of HDW, to test how sensitive HDW is to different types of meteorological data with different temporal and spatial resolutions, and to examine of how alternative formulations of HDW vary on finer spatial and temporal scales. These studies will help inform the potential for HDW to anticipate the impacts of wind shifts, thunderstorm outflows, firebrand transport and spotting, orographic circulations, and other complex phenomena during a wildland fire.

Research Results

Charney, Joseph J; Srock, A.; Potter, B.; Goodrick, S.; McDonald, J.  The Hot-Dry-Windy Index: a New Fire Weather Index. Fire on the 5s webinar. 25 July, 2018. (webinar)

Srock, Alan; Charney, Joseph; Potter, Brian; Goodrick, Scott. 2018. The hot-dry-windy index: A new fire weather index. Atmosphere. 9(7): 279-289. 11 p. https://doi.org/10.3390/atmos9070279.

McDonald, Jessica; Srock, Alan; Charney, Joseph. 2018. Development and Application of a Hot-Dry-Windy Index (HDW) Climatology. Atmosphere. 9(7): 285. 13 p. https://doi.org/10.3390/atmos9070285.

Alan F. Srock, Saint Cloud State Univ., Saint Cloud, MN; and J. J. Charney, B. E. Potter, R. Heffernan, L. Van Bussum, and S. L. Goodrick. Developing and Validating a New Fire-Weather Index Using R2O. 98th AMS Annual Meeting. 7-11 January 2018, Austin, TX.

McKenzie Kulseth, Michigan State University, East Lansing, MI; and J. J. Charney, A. F. Srock, and S. Zhong. An Inter-comparison of Hot-Dry-Windy Index values using Multiple Meteorological Datasets. 33rd Conference on Agricultural and Forest Meteorology/12th Fire and Forest Meteorology Symposium/Fourth Conference on Biogeosciences. 14-17 May 2018, Boise, ID.

Joseph J Charney, A. Srock, B. Potter, S. Goodrick.  The Hot-Dry-Windy Index: a New Fire Weather Index. National Weather Service Incident Meteorologists webinar. 12 July, 2017. (webinar)

Srock, Alan; Charney, Joseph; Goodrick, Scott; Potter, Brian. “Introducing and Validating a New Fire Weather Index: The Hot-Dry-Windy (HDW) Index.” Proceedings of the 5th International Fire Behavior and Fuels Conference, April 2016, International Association of Wildland Fire. 

Potter, Brian; Goodrick,Scott; Srock, Alan; Charney, Joseph. “Testing the Hot-Dry-Windy Index for the 2015 Fire Season in the Pacific Northwest.” Proceedings of the 5th International Fire Behavior and Fuels Conference, April 2016, International Association of Wildland Fire. 

Charney, J. J.; Srock, A. F.; Potter, B. E.; Goodrick, S. L. 2015. Historic fire weather indices: Development and implementation.  Proceedings of the 11th Symposium on Fire and Forest Meteorology, 4-7 May 2015, Minneapolis, MN, American Meteorological Society. 

Goodrick, S.; Potter, B. E.; Charney, J. J.; Srock, A. F. 2015. What would the ideal fire weather index look like?  Proceedings of the 11th Symposium on Fire and Forest Meteorology, 4-7 May 2015, Minneapolis, MN, American Meteorological Society.

Potter, B. E.; Goodrick, S. L.; Srock, A. F.; Charney, J. J. 2015. Evaluation of a suite of simple fire indices for the 2014 fire season in the Pacific Northwest.  Proceedings of the 11th Symposium on Fire and Forest Meteorology, 4-7 May 2015, Minneapolis, MN, American Meteorological Society. 

Srock, A. F.; Charney, J. J.; Goodrick, S. L.; Potter, B. E.  2015.  Investigating simple fire weather indices using reanalysis data.  Proceedings of the 11th Symposium on Fire and Forest Meteorology, 4-7 May 2015, Minneapolis, MN, American Meteorological Society. 

Research Participants

  • Last modified: March 6, 2019