How Rare Was the August 2016 South-Central Louisiana Heavy Rainfall Event?

Abstract

Abstract This study examines the spatiotemporal characteristics of the historic 10 – 14 August 2016 south-central Louisiana precipitation event. The storm was the result of a moisture-rich, tropical low pressure system, also known as a tropical easterly wave, that slowly tracked westward along the Gulf Coast from Florida to Texas. Once over south-central Louisiana, the storm was able to take advantage of anomalously high precipitable water, broad low-level instability, and continuous moisture inflow from the Gulf of Mexico to produce historic rainfall. Totals exceeded 254 mm (10 in.) for much of southern Louisiana, while locations adjacent to Baton Rouge and Lafayette received upward of 635 mm (25 in.). One station measured a 48-h rainfall total of 797.3 mm (31.39 in.)—the greatest 48-h total on record for Louisiana. Using calibrated radar data, the Storm Precipitation Analysis System (SPAS) revealed that one location likely received >864 mm (34 in.) of precipitation during the duration of the storm, well over the estimated 1000-yr return interval. A synoptic discussion of the event and analysis of the storm’s recurrence interval helps place this storm in a historical context.