The Great Flood of summer 1993: Mississippi River discharge studied

Abstract

In the summer of 1993, the Mississippi River basin in the midwestern United States experienced anomalously high rainfall. Record flooding resulted from an abnormally persistent atmospheric weather pattern consisting of a quasi‐stationary jet stream positioned over the central part of the nation, where moist, unstable air flowing north from the Gulf of Mexico converged with unseasonably cool, dry air moving south from Canada. In concert with the persistent weather pattern over the United States, highly anomalous circulation patterns were observed over much of the Northern Hemisphere [Richards, 1994]. The rainfall anomalies over the central United States produced abnormally high river discharges along the Louisiana coastline from the Mississippi and Atchafalaya Rivers during July and August, traditionally months of low river discharge. Some of the river water discharged into the northern Gulf of Mexico reached the Straits of Florida by September 1993 [Lee et al., 1994].