Floridian Heat Waves in a Warming World: Frequency, Intensity, Duration, and Linkages to Extreme Precipitation
There exists broad scientific consensus that heatwaves are increasing in frequency, duration, and intensity in a warming world, and are generally the most strongly linked extreme weather event to anthropogenic climate change. Due to its predominantly maritime climate, few studies have examined heatwaves in Florida. However, Florida’s older-skewed population and increasingly urbanized land areas make it particularly susceptible to heat impacts on human life and health in the 21st century. For the first time, this study establishes an objective heatwave metric, climatology, and trend analysis for major cities in Florida from 1950–2015. Using a percentile-based heatwave definition applied to station daily temperature data, trends in frequency, intensity, and duration of heatwaves at seven major airports across Florida are investigated. Results show that the frequency and duration of Floridian heatwaves have increased over the past 66 years, but the intensity of heatwaves have not changed significantly. Because heatwaves are generally associated with high-pressure systems that act to warm and moisten the incipient air mass, particularly in maritime tropical climates like Florida, it is hypothesized that anomalously extreme precipitation events are enhanced following the termination of a heatwave. The dynamic-thermodynamic evolution of, and physical mechanisms responsible for, extreme precipitation events in the three days following a heatwave are investigated. Results show that anomalously large subtropical moisture and moisture flux convergence related to the position of the Bermuda High, along with moderate instability, are key features in determining whether an extreme precipitation event will follow a Floridian heatwave.