Regional characteristics of flash droughts across the United States

Rapid intensification toward drought, also known as flash drought, is a subseasonal feature of the climate system whereby the persistence of extreme atmospheric anomalies for several weeks can quickly deplete soil moisture and dramatically increase evaporative stress on the environment. These events can lead to significant impacts on agricultural production during the growing season. This study performs a climatological regional analysis across the United States to explore geographic differences that exist in the rapid onset and development of drought. The Standardized Evaporative Stress Ratio (SESR) is applied to a reanalysis dataset to quantify regional flash drought characteristics across nine climate regions in the United States. May and June had a higher frequency of flash drought events in the western United States, while a climatological peak in flash drought frequency was found in July and August for the eastern United States. For all climate regions, flash drought intensity was found to increase throughout the beginning of the growing season, then decrease in the latter portion of the growing season. Analysis of preceding moisture conditions revealed that antecedent dry conditions increased flash drought risk for all regions. Lastly, less than half of all flash droughts persisted to hydrological drought across the United States.