EXPLORING SPATIOTEMPORAL TRENDS AND HOTSPOTS IN HEAVY PRECIPITATION IN TENNESSEE COUNTIES

Heavy precipitation patterns are changing in response to climate change. Spatiotemporal analysis, a uniquely appropriate geographic tool, was used to analyze trends and identify emerging hotspots / coldspots in heavy precipitation in Tennessee counties. For each Tennessee county, rainfall frequency duration estimates of 24-hour rainfall events for 1-, 2-, and 5-year return periods were extracted from the NOAA Rainfall Atlas and daily (24-hour) rainfall accumulation from 1991-2022 were downloaded from the PRISM Climate Dataset using the closest weather stations to the county centroid. For all return periods, heavy precipitation events were increasing: 1-year heavy precipitation trended up in 19 counties distributed across the state with a downtrend in 1 county. Uptrends in 2-year heavy precipitation were identified in 17 counties with downtrends in 2 counties and uptrends in 5-year heavy precipitation were identified in 7 counties. All these trends were at a 90% or higher confidence level. Middle Tennessee was identified as a heavy precipitation sporadic and consecutive hotspot for 1-, 2-, and 5-year return periods. The results confirm a widespread and consistent increase in heavy precipitation events across Tennessee counties. This study is an important step toward understanding spatiotemporal trends in heavy precipitation events and will be useful in hazard mitigation planning in Tennessee at both state and county levels.