The wildfire impacts of the 2017-2018 precipitation whiplash event across the Southern Great Plains

Abstract

The Southern Great Plains of the United States is a region with a sharp zonal precipitation gradient that is prone to rapid transitions in precipitation extremes. Transitions from pluvial to drought conditions can lead to the green-up of vegetation during extreme rainfall, posing a considerable fire risk as the region rapidly transitions into drought. Such transitions have been studied in depth across regions such as California; however, limited studies have examined their impacts across the Southern Great Plains. The aim of this study was to examine the role of preceding precipitation whiplash events in providing fuel for wildfires, with 2017–2018 investigated as a case study. This study specifically demonstrates the relationship between precipitation, vegetation, and wildfires for the first time across the Southern Great Plains. Lag correlation analysis of historical data at our study site showed anomalously high precipitation 8 months prior to Spring wildfires, resulting in a significantly higher number of wildfires and acres burned. In particular, this study examined a highly impactful precipitation whiplash event that occurred during the Fall of 2017 across the Oklahoma and Texas panhandles, which preceded a mega-fire event in the Spring of 2018. Precipitation anomalies that were 137% of normal during the 2017 growing season rapidly cascaded into drought conditions with precipitation anomalies 21% of normal throughout the cool winter season. Excessive precipitation supported vigorous vegetation recovery and growth, with vegetation indices peaking at approximately 1 standard deviation above average during August 2017. However, the subsequent drought period rapidly desiccated the terrestrial surface. As a result, dozens of wildfires burned a total of 556 347 acres during March and April 2018, resulting in at least two fatalities, dozens of homes destroyed, and over 500 personnel dispatched to fight and mitigate the fires. Overall, this study highlights the significant role of preceding Fall precipitation whiplash events in fueling Spring wildfires across the Southern Great Plains, particularly exemplified by the impactful 2017–2018 case, highlighting the complex dynamics between extreme precipitation, vegetation growth, and subsequent fire risks in the region.

Keywords

• drought
• pluvial
• wildfire
• precipitation whiplash