Regional Characteristics of Flash Droughts across the United States

This study focused on quantifying regional characteristics of flash drought development and intensification across the United States using the North American Regional Reanalysis (NARR) dataset. Flash droughts are identified by using a percentile-based methodology that utilizes the evaporative stress ratio (ESR; the ratio between evapotranspiration and potential evapotranspiration). Two criteria in the methodology emphasize vegetative impact, while two additional criteria emphasize the rate of intensification of drought. Previous results illustrating the frequency of flash drought events across the United States demonstrated that regional differences of flash droughts exist. A directory of flash drought events from the NARR dataset spanning from 1979-2016 in the growing season was compiled and used to quantify regional flash drought characteristics such as transitions of flash drought events to long-term drought, temporal hot spots of flash droughts, evaporative stress conditions preceding flash drought events, and relationships between soil moisture and flash drought development. The results were aggregated into the nine United States climate regions identified by the National Centers for Environmental Information.