A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds, and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.
The Fujita scale, or Fujita–Pearson scale, is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is determined by meteorologists and engineers after a ground or aerial damage survey, or both; and depending on the circumstances, ground-swirl patterns, weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording is available. The Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale) in the United States in February 2007. In April 2013, Canada adopted the EF-Scale over the Fujita scale along with 31 "Specific Damage Indicators" used by Environment Canada (EC) in their ratings.
A tornado watch is issued when weather conditions are favorable for the development of severe thunderstorms that are capable of producing tornadoes. A tornado watch therefore implies that it is also a severe thunderstorm watch. A tornado watch must not be confused with a tornado warning. In most cases, the potential exists for large hail and/or damaging winds in addition to tornadoes.
These are some notable tornadoes, tornado outbreaks, and tornado outbreak sequences that have occurred around the globe.
- Exact death and injury counts are not possible; especially for large events and events before 1955.
- Prior to 1950 in the United States, only significant tornadoes are listed for the number of tornadoes in outbreaks.
- Due to increasing detection, particularly in the U.S., numbers of counted tornadoes have increased markedly in recent decades although the number of actual tornadoes and counted significant tornadoes has not. In older events, the number of tornadoes officially counted is likely underestimated.
A tornado is a violent rotating column of air that touches the surface of the earth.
Tornado Alley is a colloquial term for the area of the United States where tornadoes are most frequent.
Tornado myths are incorrect beliefs about tornadoes, which can be attributed to many factors, including stories and news reports told by people unfamiliar with tornadoes, sensationalism by news media, and the presentation of incorrect information in popular entertainment. Common myths cover various aspects of the tornado, and include ideas about tornado safety, the minimization of tornado damage, and false assumptions about the size, shape, power, and path of the tornado itself.
A tornado outbreak is the occurrence of multiple tornadoes spawned by the same synoptic scale weather system. The number of tornadoes required to qualify as an outbreak typically are at least six to ten.
The Enhanced Fujita scale (EF-Scale) rates the intensity of tornadoes in some countries, including the United States and Canada, based on the damage they cause.
The 1989 Northeastern United States tornado outbreak was a series of tornadoes which caused more than $130 million in damage across the Northeastern United States on July 10, 1989. The storm system affected five states with severe weather, including hail up to 2.5 inches (6.4 cm) across, thunderstorm winds up to 90 mph (140 km/h), and 17 tornadoes. Several towns in New York and Connecticut were particularly hard-hit. Several homes were leveled in Schoharie, New York and extensive damage occurred in Bantam, Connecticut. A large section of Hamden, Connecticut, including an industrial park and hundreds of homes, was destroyed; and in some places buildings were flattened to the ground.
Tornadoes have been recorded on all continents except Antarctica and are most common in the middle latitudes where conditions are often favorable for convective storm development. The United States has the most tornadoes of any country, as well as the strongest and most violent tornadoes. A large portion of these tornadoes form in an area of the central United States popularly known as Tornado Alley. Canada experiences the second most tornadoes. Ontario and the prairie provinces see the highest frequency, particularly with southward extent. Other areas of the world that have frequent tornadoes include significant portions of Europe, South Africa, Philippines, Bangladesh, parts of Argentina, Uruguay, and southern and southeast Brazil, northern Mexico, New Zealand, and far eastern Asia.
Severe weather refers to any dangerous meteorological phenomena with the potential to cause damage, serious social disruption, or loss of human life. Types of severe weather phenomena vary, depending on the latitude, altitude, topography, and atmospheric conditions. High winds, hail, excessive precipitation, and wildfires are forms and effects of severe weather, as are thunderstorms, downbursts, tornadoes, waterspouts, tropical cyclones, and extratropical cyclones. Regional and seasonal severe weather phenomena include blizzards (snowstorms), ice storms, and duststorms.
The March 1952 Southern United States tornado outbreak was the ninth deadliest tornado outbreak in the history of the United States. Affecting the American South, it produced 209 deaths, 50 of which were related to a single tornado in Arkansas. The outbreak produced 11 violent F4 tornadoes across the Southern United States, which is the fourth-largest number of F4–F5 events produced by a single outbreak. Only the 1965 Palm Sunday tornado outbreak, the 1974 Super Outbreak, and the 2011 Super Outbreak surpassed this number. The severe weather event resulted in the fourth-largest number of tornado fatalities within a 24-hour period since 1950. The weather system associated with the outbreak also produced several inches of snow across the central and northern Great Plains and the upper Midwest. Blizzard conditions affected Kansas, Nebraska, and South Dakota.
The tornado outbreak of April 9–11, 2009 was a tornado outbreak that affected large portions of the Southern United States on April 9–11, 2009. At least 5 people were killed by tornadoes including three in Mena, Arkansas and two in Murfreesboro, Tennessee just south of Nashville. A total of 85 tornadoes were confirmed over the two days. Three people were killed in Texas due to wildfires caused by strong winds stemming from the same storm system.
This page documents notable tornadoes and tornado outbreaks worldwide in 2019. Strong and destructive tornadoes form most frequently in the United States, Argentina, Brazil, Bangladesh, and Eastern India, but can occur almost anywhere under the right conditions. Tornadoes also develop occasionally in southern Canada during the Northern Hemisphere's summer and somewhat regularly at other times of the year across Europe, Asia, Argentina, and Australia. Tornadic events are often accompanied by other forms of severe weather, including strong thunderstorms, strong winds, and hail.
