page_title: 2011 Super Outbreak
hierarchical_section_title: 2011 Super Outbreak
caption_attribution_description: English: April 27 and April 28, 2011, brought the deadliest tornado outbreak in the United States since 1974. By dawn on April 28, at least 250 people had been killed in 6 states. Alabama was the hardest hit state, with 162 confirmed dead as of Thursday morning. This image shows the storms at 1:45 p.m. U.S. Central Daylight Time, and the animation shows the development of the weather system that spurred the widespread deadly tornadoes. The images are from the GOES satellite. The animation starts on April 26 and goes through the morning of April 28. The ingredients for severe weather are evident in the cloud patterns. Throughout the period, a relatively stable mass of cold air—visible as a swirl of more-or-less continuous clouds—rotates in the north along the top of the image. Meanwhile, moist air pushes north and west from the Atlantic and Gulf of Mexico. The warm air contains small low clouds. The collision between two such air masses is enough to generate severe weather, but the weather was amplified by the jet stream on April 27. Though not directly visible in the image, the narrow band of fast-moving wind that makes up the jet stream blew north and east between the two air masses. Surface winds blowing from the south and east and the jet stream blowing in from the west set up powerful smaller-scale circulations that generated lines of intense thunderstorms. The thunderstorms shown in this image began to rise over Louisiana midway through the day on April 27—around 16:00 UTC or 11:00 a.m. local time, and moved across Mississippi and Alabama through the afternoon. Forming along and ahead of the turbulent boundary between the two air masses, the storms are moving east and north with the jet stream. The bright white spots within the clouds are very active storms, quite probably the systems that generated tornadoes. Throughout the day, many such storms rose over the south. The slow eastward progression of the upper-level system permitted successive storms to affect the same region for a much longer time span than is typical. According to the National Weather Service, more than 150 tornadoes were reported throughout the day. The images in this animation are from the GOES satellite, a geostationary satellite whose orbit keeps it above the same spot on Earth at all times. Such an orbit allows the satellite to image the movement of clouds every few minutes, observations that are necessary for weather monitoring and forecasting. GOES is a joint NASA and NOAA satellite.
context_page_description: The 2011 Super Outbreak was the largest, costliest, and one of the deadliest tornado outbreaks ever recorded, taking place along the Southern, Midwestern, and Northeastern United States and leaving catastrophic destruction in its wake. The event not only affected Alabama and Mississippi the most severely, but also produced destructive tornadoes in Arkansas, Georgia, Tennessee and Virginia, and affected many other areas throughout the Southern and Eastern United States. In total, 360 tornadoes were confirmed by NOAA's National Weather Service and Government of Canada's Environment Canada in 21 states from Texas to New York to southern Canada. Widespread and destructive tornadoes occurred on each day of the outbreak, with April 27 being the most active day with a record of 216 tornadoes touching down that day from midnight to midnight CDT. Four of the tornadoes were destructive enough to be rated EF5, which is the highest ranking possible on the Enhanced Fujita scale; typically these tornadoes are only recorded about once each year or less.
context_section_description: The 2011 Super Outbreak was the largest, costliest, and one of the deadliest tornado outbreaks ever recorded, taking place along the Southern, Midwestern, and Northeastern United States and leaving catastrophic destruction in its wake. The event not only affected Alabama and Mississippi the most severely, but also produced destructive tornadoes in Arkansas, Georgia, Tennessee and Virginia, and affected many other areas throughout the Southern and Eastern United States. In total, 360 tornadoes were confirmed by NOAA's National Weather Service (NWS) and Government of Canada's Environment Canada in 21 states from Texas to New York to southern Canada. Widespread and destructive tornadoes occurred on each day of the outbreak, with April 27 being the most active day with a record of 216 tornadoes touching down that day from midnight to midnight CDT (0500 – 0500 UTC). Four of the tornadoes were destructive enough to be rated EF5, which is the highest ranking possible on the Enhanced Fujita scale; typically these tornadoes are only recorded about once each year or less.
  In total, 348 people were killed as a result of the outbreak, which includes 324 tornado-related deaths across six states and an additional 24 fatalities caused by other thunderstorm-related events such as straight-line winds, hail, flash flooding or lightning. In Alabama alone, 238 tornado-related deaths were confirmed by the Storm Prediction Center (SPC) and the state's Emergency Management Agency.
  April 27's 316 fatalities were the most tornado-related fatalities in the United States in a single day since the "Tri-State" outbreak on March 18, 1925 (when at least 747 people were killed). Nearly 500 preliminary local storm reports were received for tornadoes over four days, including 292 in 16 states on April 27 alone. This event was the costliest tornado outbreak in United States history, with total damage reaching $10.2 billion (2011 USD).
caption: The storm system responsible for the historic tornado outbreak on April 27
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