Precipitation Whiplash Events Across the Southern Great Plains of the United States

Abstract

The Southern Great Plains is a region that is prone to precipitation extremes and transitions between them which have direct impacts on agriculture, infrastructure, water quality and water quantity. However, current understanding of transitions between precipitation extremes, including seasonal and annual characteristics as well as spatial and temporal patterns across the Southern Great Plains (SGP) is lacking. Most previous research has focused primarily on the characteristics and impacts of transitions on the annual scale, and those that have investigated shorted timescales have not completed an analysis across the Southern Great Plains. In this study, the characteristics and climatology of transitions between precipitation extremes on the subseasonal-to-seasonal (S2S) scale across the Southern Great Plains between 1981 and 2018 were examined. Transitions between precipitation extremes were defined using a percentile method where S2S precipitation totals at individual grid points are ordered. A transition from the low (high) percentile threshold to the high (low) percentile threshold from one period to the next were defined to be a drought-pluvial (pluvial-drought) transition. At least one transition event was found to occur somewhere within the Southern Great Plains every year between 1981 and 2018, with the Fall season being the time of year when these events are most likely to occur. The months of September and October are the most common months to be drought and pluvial months suggesting that the secondary peak in annual precipitation that is observed during the Fall is important in driving transitions in precipitation extremes across the SGP. One such example of a precipitation whiplash event occurred across the SGP in 2017. Above average precipitation totals throughout the year fell below average during the Fall period and the region transitioned from pluvial to drought conditions during the months of September to October. The insight this study gives into the climatology of transitions in precipitation extremes on the subseasonal scale will greatly enhance the understanding of these events allowing for better predictability and preparedness into the future.