Type Tornado outbreak Max rating | Tornadoes confirmed 32 | |
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Duration August 27–September 4, 2012 Duration of tornado outbreak 8 days, 15 hours, 22 minutes Damage $6.38 million (2012 USD) | ||
The 2012 Hurricane Isaac tornado outbreak was a tropical cyclone-produced severe-weather event that affected the U.S. states of Florida, Mississippi, Alabama, Louisiana, Missouri, and Illinois from August 27 to September 4, 2012. Hurricane Isaac produced a total of 34 tornadoes, with the strongest being two EF2s in Mississippi and Arkansas. 19 tornado watches were issued for Isaac over eight days. 171 tornado warnings covered 12 states, with Mississippi being issued the most at 77.
Event summary
A tropical wave emerged off the western coast of Africa into the Atlantic Ocean on August 16. After acquiring a well-defined center of circulation and deep atmospheric convection, the disturbance was deemed organized enough to be declared a tropical depression by 06:00 UTC on August 21 while located about 720 mi (1,160 km) east of the Lesser Antilles. Twelve hours later, the depression intensified into Tropical Storm Isaac. Steered swiftly westward across the eastern Caribbean Sea by a subtropical ridge, the cyclone steadily intensified prior to making landfall near Jacmel, Haiti with winds of 65 mph (100 km/h) by 06:00 UTC on August 25; a few hours later, Isaac moved ashore near Cajobabo, Guantánamo, Cuba with winds of 60 mph (95 km/h). After moving through the Straits of Florida and into the eastern Gulf of Mexico, the system initially struggled to organize as its wind field expanded. By 12:00 UTC on August 28, however, data from an aircraft reconnaissance flight supported designating Isaac as a Category 1 hurricane. The cyclone attained peak winds of 80 mph (130 km/h) prior to making two landfalls, one at the Southwest Pass over the Mississippi River and the second near Port Fourchon, Louisiana. Once inland, Isaac steadily weakened and dissipated over Missouri early on September 1.
On August 22, the Storm Prediction Center noted the potential for severe weather to evolve in association with Isaac; however, considerable model uncertainty precluded the addition of a threat area. Three days later, a severe threat area was outlined across southern Georgia, southeastern Alabama, and northern Florida as the outer bands of the hurricane were forecast to rotate into the region.