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A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The windstorm is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 110 miles per hour (180 km/h), are about 250 feet (80 m) across, and travel a few miles before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (480 km/h), are more than two miles (3 km) in diameter, and stay on the ground for dozens of miles.
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 mesocyclone is storm-scale region of rotation (vortex), typically around 2 to 6 mi in diameter, within a thunderstorm. In the northern hemisphere it is particularly found in the right rear flank of a supercell or often on the eastern, or front, flank of an HP storm. The circulation of a mesocyclone covers an area much larger than the tornado that may develop within it.
A tornado warning is an alert issued by national weather forecasting agencies to warn the public that severe thunderstorms with tornadoes are imminent or occurring. It can be issued after a tornado, funnel cloud and rotation in the clouds has been spotted by the public, storm chasers, emergency management or law enforcement.
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1890 until it adopted its current name in 1970.
NEXRAD or Nexrad is a network of 159 high-resolution S-band Doppler weather radars operated by the National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of Commerce, the Federal Aviation Administration (FAA) within the Department of Transportation, and the U.S. Air Force within the Department of Defense. Its technical name is WSR-88D.
Storm chasing is broadly defined as the pursuit of any severe weather condition, regardless of motive, which can be curiosity, adventure, scientific investigation, or for news or media coverage.
The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs).
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce (DoC), defines precise meanings for nearly all of its weather terms.
The Enhanced Fujita scale rates the intensity of tornadoes in some countries, including the United States and Canada, based on the damage they cause.
Gary England is the former chief meteorologist for KWTV, the CBS-affiliated television station in Oklahoma City, Oklahoma. England was the first on-air meteorologist to alert his viewers of a possible tornado using a commercial Doppler weather radar. He is also known for contributing to the invention of the First Warning map graphic commonly used to show ongoing weather alerts without interrupting regular programming. Currently, Gary is the Vice President of Corporate Relations and Weather Development at Griffin Communications LLC, the parent company to KWTV-DT, although the company uses the same single-story building as the studio.
First Warning is the name of a severe weather warning system designed for broadcast television stations, typically those in the United States. A weather advisory product based on First Warning, called First Alert, is an automated version of this product, which has come into widespread use by television stations and is marketed under different names depending on the graphics service vendor.
Volumetric Imaging and Processing of Integrated Radar, known by the acronym VIPIR, is an analysis and display program for Doppler weather radar, created and sold by Baron Services. This software allows improved analysis of radar data for private users, in particular television stations, similar to the Weather Decision Support System program used by the National Weather Service.
A tornado emergency is an enhanced version of a tornado warning, which is used by the National Weather Service (NWS) in the United States during imminent, significant tornado occurrences in highly populated areas. Although it is not a new warning type from the NWS, issued instead within a severe weather statement or in the initial tornado warning, a tornado emergency generally means that significant, widespread damage is expected to occur and a high likelihood of numerous fatalities is expected with a large, strong to violent tornado.
The 2008 Super Tuesday tornado outbreak was a deadly tornado outbreak which affected the Southern United States and the lower Ohio Valley on February 5 and 6, 2008. The event began on Super Tuesday, while 24 states in the United States were holding primary elections and caucuses to select the presidential candidates for the upcoming presidential election. Missouri, Illinois, Arkansas, Alabama, and Tennessee were among the affected regions in which primaries were being held. Some voting locations were forced to close early due to the approaching severe weather.
Baron Services is a weather technology company based in Huntsville, Alabama, United States. The company develops weather systems that aid in the detection and dissemination of weather information to customers in the broadcast, government, aviation, marine and automotive industries. These technologies include weather tracking software, Doppler weather radar, systems integration, and personal alerting services, among others. The company holds numerous U.S. patents for weather technology.
The 1999 Bridge Creek–Moore tornado was a large and extraordinarily powerful F5 tornado in which the highest wind speeds ever measured globally were recorded at 301 ± 20 miles per hour (484 ± 32 km/h) by a Doppler on Wheels (DOW) radar. Considered the strongest tornado ever recorded to have affected the Oklahoma City metropolitan area, the tornado devastated southern portions of Oklahoma City, Oklahoma, United States, along with surrounding suburbs and towns to the south and southwest of the city during the early evening of Monday, May 3, 1999. The tornado covered 38 miles (61 km) during its 85-minute existence, destroying thousands of homes, killing 36 people, and leaving US$1 billion in damage, ranking it as the fifth-costliest on record not accounting for inflation.
During the early evening of Friday, May 31, 2013, a very large and powerful tornado occurred over rural areas of Central Oklahoma. This rain-wrapped, multiple-vortex tornado was the widest tornado ever recorded and was part of a larger weather system that produced dozens of tornadoes over the preceding days. The tornado initially touched down at 6:03 p.m. Central Daylight Time (2303 UTC) about 8.3 miles (13.4 km) west-southwest of El Reno, rapidly growing in size and becoming more violent as it tracked through central portions of Canadian County. Remaining over mostly open terrain, the tornado did not impact many structures; however, measurements from mobile weather radars revealed extreme winds up to 302 mph (486 km/h) within the vortex; these are the second-highest observed wind speeds on Earth, behind the 1999 Bridge Creek–Moore tornado which had slightly higher wind speeds. As it crossed U.S. Highway 81, it had grown to a record-breaking width of 2.6 miles (4.2 km). Turning northeastward, the tornado soon weakened. Upon crossing Interstate 40, the tornado dissipated around 6:43 p.m. CDT (2343 UTC), after tracking for 16.2 miles (26.1 km), it avoided affecting the more densely populated areas near and within the Oklahoma City metropolitan area.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
References
- ↑ Baron Services: About BTI Archived 2008-03-03 at the Wayback Machine
- ↑ "Small Scale for the Big Screen". Broadcasting & Cable. 2008-02-04.
- ↑ "Deployed Guardsman Uses Station's Online Video to Give Family Tornado Info". TVtechnology.com. 2008-02-29.
- ↑ "New Baron Tornado Index predicts likelihood of twisters". Broadcast Engineering. 2008-01-25. Archived from the original on 2008-05-14.
- ↑ "Station's Severe Weather Coverage Results in Big Ratings Boost" (PDF). Baron Services. Archived from the original (PDF) on 2010-11-20. Retrieved 2008-05-13.
