Spatiotemporal analysis of extreme precipitation in the southern Great Plains hydroclimate region

Authors: Flanagan, Paul; MAHMOOD, REZAUL - University Of Nebraska

Submitted to: Journal of Applied Meteorology and Climatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2022
Publication Date: 3/1/2023
Citation: Flanagan, P.X., Mahmood, R. 2023. Spatiotemporal analysis of extreme precipitation in the southern Great Plains hydroclimate region. Journal of Applied Meteorology and Climatology. 62(3):393-409. https://doi.org/10.1175/JAMC-D-22-0071.1.
DOI: https://doi.org/10.1175/JAMC-D-22-0071.1

Interpretive Summary: Owing to the vital importance of water to the Southern Great Plains (SGP), understanding the nature and changes in precipitation is crucial. While drought has received much more attention, extreme precipitation events can be harmful to the SGP region as well. While extreme precipitation events have been previously investigated within the region, most of these studies have focused on the regional aspect of extreme precipitation changes, rather than a station-based assessment of these events. In this study, trends in extreme precipitation will be investigated at the station level during the period from 1950 – 2020 using 108 stations from the SGP region. Result showed that two patterns of extreme precipitation event changes exist across the SGP, one in the eastern SGP and one in the western SGP. Eastern SGP extreme precipitation is increasing in magnitude and frequency in a climate where these events were already particularly common. In the western SGP, these events are rather common and only appear to be changing in terms of spatial coverage across the 1950 – 2020 period. Overall, it was seen that seasonal and annual changes in extreme precipitation events are evident across the SGP. While this study was not the first to investigate extreme precipitation in the SGP, our results show distinctly new details that will aid in focusing future research into extreme precipitation in the SGP.

Technical Abstract: The Southern Great Plains (SGP) is a region defined by hydrometeorological swings between dry and wet, drought and flood. These swings exacerbate the climatological gradients between moisture (east to west) and temperature (south to north), which can detrimentally impact the agricultural production key to the economy of the region. Thus, it is key to understand changes in extremes, wet or dry, hot or cold, to sustainably maintain the agricultural success in the region. This study investigates the wet extremes, or extreme precipitation events, that have become more prominent in the last two decades. 108 USHCN stations, with less than 10% missing data, were investigated from 1950 – 2020 to detect changes in the frequency and magnitude of extreme precipitation events. Results showed that shifts in the magnitude and frequency are occurring across the SGP. Magnitude shifts in the eastern portion of the SGP were evident, especially in the central corridor in which the low-level jet is a key driver of moisture return and precipitation. Shifts in the frequency of extreme precipitation events were detected across the entire SGP, however, these shifts in frequency appear to be caused more so by increasing spatial coverage of extreme precipitation rather than being singularly caused by an increase in the number of events themselves. Further, seasonal analysis of extreme precipitation showed the key differences in changes that have occurred across the cold and warm season of the SGP. Overall, these results depict the changing nature of extreme precipitation within the SGP and the key differences between extreme precipitation in the eastern and western SGP.