Program Manager Dr. Vincent Brown and Principle Investigator Dr. Barry Keim of the Southern Climate Impacts Planning Program (SCIPP), a CPO RISA team, at Louisiana State University recently published two manuscripts related to precipitation extremes in the Southeast United States. The first manuscript titled “How Rare Was the August 2016 South-Central Louisiana Heavy Rainfall Event?”, published in the Journal of Hydrometeorology (April 2020), found that an area roughly 5000 mi2 in Southern Louisiana received approximately 18.3 inches of precipitation in only 96 hours during the August 2016 event. A precipitation gauge recorded 31.39 inches of rain in just 48 hours (a record for Louisiana) and their analysis revealed one location likely received over 34 inches of rain during the event. The authors completed the study through close work with Applied Weather Associates (AWA) using the Storm Precipitation Analysis System (SPAS), a software product owned by AWA, to analyze the spatiotemporal pattern of precipitation in detail. The manuscript details the synoptic setting of the event and uses recurrence intervals to help place the storm in a historical context. This manuscript is a good example of how SCIPP interacts with other entities (in this case AWA) to conduct research and generate information.
The second manuscript titled “Trend Analysis of Multiple Extreme Hourly Precipitation Time Series in the Southeastern United States,” was published in the Journal of Applied Meteorology and Climatology in March 2020. During the study period (1960-2017), the annual magnitude of the greatest 1-,3-,6-,12-, and 18- hourly periods did not show any spatially congruent trends, revealing that the biggest annual hourly precipitation events did not change in magnitude in the region. However, the magnitude of annual hourly 90th percentile events increased significantly at 36% of the sites analyzed, demonstrating that hourly magnitude is increasing at some stations in the Southeast United States. This shows that while the heaviest hourly precipitation events in a year are not increasing in magnitude, lesser hourly events (still of a high magnitude) are becoming heavier on average. The study also highlights changes in the longest hourly precipitation events and dry spell duration in the region. The research complements a previous manuscript published by the same authors titled “Climatology and Trends in Hourly Precipitation for the Southeast United States” (Journal of Hydrometeorology in August 2019) and highlights changes in extreme hourly precipitation time series.
