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.
A mesocyclone is a meso-gamma mesoscale region of rotation (vortex), typically around 2 to 6 mi in diameter, most often noticed on radar within thunderstorms. In the northern hemisphere it is usually located in the right rear flank of a supercell, or often on the eastern, or leading, flank of a high-precipitation variety of supercell. The area overlaid by a mesocyclone’s circulation may be several miles (km) wide, but substantially larger than any tornado that may develop within it, and it is within mesocyclones that intense tornadoes form.
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).
Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile process and the intricacies of many of the mechanisms of tornado formation are still poorly understood.
Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft.
A tornadic vortex signature, abbreviated TVS, is a Pulse-Doppler radar weather radar detected rotation algorithm that indicates the likely presence of a strong mesocyclone that is in some stage of tornadogenesis. It may give meteorologists the ability to pinpoint and track the location of tornadic rotation within a larger storm, and is one component of the National Weather Service's warning operations.
Charles A. Doswell III is an American meteorologist and prolific severe convective storms researcher. Doswell is a seminal contributor, along with Leslie R. Lemon, to the modern conception of the supercell, which was developed originally by Keith Browning. He also has done research on forecasting and forecast verification, especially for severe convective storms, and is an advocate of ingredients-based forecasting.
The Verification of the Origins of Rotation in Tornadoes Experiment are field experiments that study tornadoes. VORTEX1 was the first time scientists completely researched the entire evolution of a tornado with an array of instrumentation, enabling a greater understanding of the processes involved with tornadogenesis. A violent tornado near Union City, Oklahoma was documented in its entirety by chasers of the Tornado Intercept Project (TIP) in 1973. Their visual observations led to advancement in understanding of tornado structure and life cycles.
Howard Bruce Bluestein is a research meteorologist known for his mesoscale meteorology, severe weather, and radar research. He is a major participant in the VORTEX projects. A native of the Boston area, Dr. Bluestein received his Ph.D. in 1976 from MIT. He has been a professor of meteorology at the University of Oklahoma (OU) since 1976.
Roger M. Wakimoto is an atmospheric scientist specializing in research on mesoscale meteorology, particularly severe convective storms and radar meteorology. A former director of the National Center for Atmospheric Research (NCAR), Wakimoto in November 2012 was appointed as assistant director of the Directorate for Geosciences (GEO) of the National Science Foundation (NSF).
Paul M. Markowski is an American meteorologist and leading expert on tornadogenesis and the forecasting of supercells and tornadoes.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
Robert Peter Davies-Jones is a British atmospheric scientist who substantially advanced understanding of supercell and tornado dynamics and of tornadogenesis. A theoretician, he utilized numerical simulations as well as storm chasing field investigations in his work as a longtime research meteorologist at the National Severe Storms Laboratory (NSSL) in Norman, Oklahoma.
Louis John Wicker is an American atmospheric scientist with expertise in numerical analysis, numerical simulation, and forecasts of severe convection and tornadoes. Doing storm chasing field research, Wicker deployed the TOtable Tornado Observatory (TOTO) and was in leadership roles in the VORTEX projects. He is also known for pioneering work simulating convection at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana–Champaign (UIUC).
Adam James Clark is an American meteorologist at the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) and the National Severe Storms Laboratory (NSSL) recognized for contributions to numerical modeling of convection.
David Owen Blanchard is an American meteorologist, photographer, and storm chaser. He was a significant collaborator in seminal research on tornadogenesis, specifically the importance of baroclinic boundaries, the rear-flank downdraft (RFD) and its thermodynamic characteristics.
Donald W. Burgess is an American meteorologist who has made important contributions to understanding of severe convective storms, particularly tornadoes, radar observations and techniques, as well as to training other meteorologists. He was a radar operator during the first organized storm chasing expeditions by the University of Oklahoma (OU) in the early 1970s and participated in both the VORTEX projects.
Yvette Richardson is an American meteorologist with substantial contributions on tornado dynamics, tornadogenesis, the environments of tornadoes, supercells, and severe convection, and radar observations of these. She was a principal investigator (PI) of VORTEX2.
David C. Dowell is American atmospheric scientist recognized for research on tornado structure and dynamics and on tornadogenesis. He participated in both of the VORTEX projects.
Roger Edwards is an American meteorologist and expert on severe convective storms (thunderstorms). He is the co-founder and editor-in-chief of the Electronic Journal of Severe Storms Meteorology (EJSSM).
