The passage of

Hurricane Isaac The name Isaac (or the variant Isaack) has been used for six tropical cyclones in the Atlantic Ocean and for one in the South Pacific Ocean, and has been used for one extratropical european windstorm. In the Atlantic: * Tropical Storm Isaac (1988) ...

generated a long-lived, nine-day tornado outbreak that affected the Central and

Eastern United States The Eastern United States, often abbreviated as simply the East, is a macroregion of the United States located to the east of the Mississippi River. It includes 17–26 states and Washington, D.C., the national capital. As of 2011, the Eastern ...

from August 27 to September 4, 2012. The hurricane produced a total of 34 tornadoes, with the strongest being two EF2 tornadoes in Mississippi and Arkansas. There were 19

tornado watch A tornado watch ( SAME code: TOA) is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of tornadoes within (or near) the region over a period of seve ...

es were issued for Isaac over eight days and 171 tornado warnings were issued across 12 states, with 77 of them in Mississippi.

Event summary

tropical wave A tropical wave (also called easterly wave, tropical easterly wave, and African easterly wave), in and around the Atlantic Ocean, is a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which ...

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 Atmospheric convection is the vertical transport of heat and moisture in the atmosphere. It occurs when warmer, less dense air rises, while cooler, denser air sinks. This process is driven by parcel-environment instability, meaning that a "par ...

, the disturbance was deemed organized enough to be declared a tropical depression by 06:00 UTC on August 21 while located about east of the

Lesser Antilles The Lesser Antilles is a group of islands in the Caribbean Sea, forming part of the West Indies in Caribbean, Caribbean region of the Americas. They are distinguished from the larger islands of the Greater Antilles to the west. They form an arc w ...

. Twelve hours later, the depression intensified into Tropical Storm Isaac. Steered swiftly westward across the eastern

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

by a

subtropical ridge The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as subtropical ridges or highs. It is a high-pressur ...

, the cyclone steadily intensified prior to making landfall near Jacmel, Haiti with winds of by 06:00 UTC on August 25; a few hours later, Isaac moved ashore near Cajobabo, Guantánamo, Cuba with winds of . After moving through the

Straits of Florida The Straits of Florida, Florida Straits, or Florida Strait () is a strait located south-southeast of the North American mainland, generally accepted to be between the Gulf of Mexico and the Atlantic Ocean, and between the Florida Keys (U.S.) an ...

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 prior to making two landfalls, one at the Southwest Pass over the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

and the second near

Port Fourchon, Louisiana Port Fourchon is Louisiana’s southernmost port, located on the southern tip of Lafourche Parish, on the Gulf of Mexico. It is a seaport, with significant petroleum industry traffic from offshore Gulf oil platforms and drilling rigs as well as ...

. Once inland, Isaac steadily weakened and dissipated over Missouri early on September 1. On August 22, the

Storm Prediction Center The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceani ...

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.

Confirmed tornadoes

August 27 event

August 29 event

August 30 event

August 31 event

September 1 event

September 3 event

September 4 event

Footnotes

References

External links

Hurricane Isaac Advisory Archive

Hurricane Isaac Advisory Graphics Archive
{{DEFAULTSORT:Hurricane Isaac tornado outbreak, 2012 Tornda Tornadoes of 2012 Tornadoes in Florida Tornadoes in Alabama Tornadoes in Illinois Tornadoes in Delaware Tornadoes in New Jersey 2012 natural disasters in the United States August 2012 in the United States September 2012 in the United States F2, EF2 and IF2 tornadoes Tornado outbreaks spawned by tropical cyclones