Tornado and Tropical Storm in Louisiana, September 10 to 12, 1998

A tropical depression in the western Gulf of Mexico was classified as Tropical Storm Frances during the afternoon of September 9th. After a period of erratic movement, Frances settled on a northwest track that brought it ashore in the early morning hours of September 11th between Port Aransas and Port Oconner, Texas. Due to the large pressure difference between Tropical Storm Frances and a high pressure system over the eastern United States, a prolonged period of strong east and southeast winds that occasionally reached tropical storm force affected coastal sections of southeast Louisiana. Peak wind gusts of 60 mph at 1029 CST on the 10th and 55 mph at 1826 PM on the 10th were recorded at the Burrwood and Grand Isle C-MAN stations, respectively. A wind gust of 62 mph was observed at a buoy in eastern Lake Pontchartrain near the Rigolets during a squall at 1510 CST on the 11th. Significant tidal flooding occurred during the event with tides averaging 2 to 4 feet above normal along the southeast Louisiana coastline and in Lakes Pontchartrain and Maurepas. The persistent strong winds and resulting high tides pushed a considerable amount of water into the tidal lakes of southeast Louisiana parishes and well inland along marshes, bayous, and other low-lying areas. This resulted in a number of homes outside of the levee protection systems being flooded and caused the flooding of many roadways. The most severe flooding occurred in Terrebonne, Lafourche, and lower Jefferson Parishes. Many businesses along the Harvey Canal in Jefferson Parish were damaged due to storm surge flooding, and the levee along the canal was nearly overtopped. In addition, very heavy rainfall occurred with most locations of southeast Louisiana receiving a minimum of 5 inches during the storm with some areas south of Lake Pontchartrain receiving 15 to 30 inches of rain. The heavy rainfall resulted in widespread flash flooding south of Lake Pontchartrain.The flash flooding peaked on September 11th when intense rainfall associated with a Tropical Storm Francis rainband resulted in rainfall amounts of 5 to 7 inches within a two to three hours period over portions of the greater New Orleans area. By late afternoon, rainfall totals had reached from 8 to 12 inches. Rainfall runoff overwhelmed drainage pumping capacity producing widespread and deep flooding in the streets of the New Orleans metropolitan area. Ground transportation throughout much of Orleans Parish and portions of adjacent parishes was brought to a near standstill during the afternoon by the flooding, stranding many at work, school, or in autos. The street flooding subsided during the evening. Around 800 homes and 30 businesses were flooded in Jefferson Parish from either storm surge flooding outside of the hurricane protection levees and flash flooding from heavy rainfall. In Orleans Parish at least 290 single family homes and 124 apartments and businesses were flooded. A tornado developed in an outer rainband associated with Tropical Storm Francis on the evening of September 10th and followed a path approximately 4 miles long from near Cut Off to Larose killing a 22 year old male in a mobile home. The most severe damage occurred in the first one half to three quarters mile of the path. Several mobile homes were destroyed, 3 conventional houses had roofs taken off, two houses were moved off their piling foundation, and two businesses suffered extensive damage. The tornado was strongest near the beginning of the track where F2 damage occurred. Over the remainder of the track, F1 damage was reported.