Geopotential Heights and Trends of the Subtropical Ridge over the Southern Great Plains and Texas Summer Fire Seasons

Higher temperatures are one component of the fire environment that may perpetuate increased wildland fire, and recent summers in Texas have been warmer. Both summertime heat and fire activity on the southern Great Plains, particularly in Texas, are modulated by the subtropical ridge. Climatologically, the subtropical ridge typically develops in mid-June, maximizes in July and August, and wanes in September. This study utilizes the National Centers for Environmental Prediction and the National Center for Atmospheric Research Reanalysis Project to investigate multidecadal 500 hPa geopotential heights for June, July, and August relative to maximum surface temperature anomalies, and the number of hectares burned in Texas during the summer fire seasons of 2005–2023. Average geopotential heights associated with a geographically consistent subtropical ridge centered over southern New Mexico and far west Texas have steadily increased from 5915 m between 1951–2023 to >5925 m from 2011–2023. These long-term increasing geopotential heights associated with the subtropical ridge are accompanied by increasingly positive maximum surface temperature anomalies and may be associated with an increase in wildfire burn areas in Texas since 2014, possibly related to a warming climate.