Mesoscale convective vortex

A mesoscale convective vortex (MCV) is a low-pressure center (mesolow) within an mesoscale convective system (MCS) that pulls winds into a circling pattern, or vortex. With a core only 30 to 60 mi (48 to 97 km) wide and 1 to 3 mi (1.6 to 4.8 km) deep, an MCV is often overlooked in standard surface observations. They have been most often been detected on radar and satellite, particularly with the higher resolution and sensitivity of WSR-88D, but with the advent of mesonets, these mesoscale features can also be detected in surface analysis. Yet an MCV can take on a life of its own, persisting for more than 12 hours after its parent MCS has dissipated. This orphaned MCV will sometimes then become the seed of the next thunderstorm outbreak. Their remnants will often lead to an "agitated area" of increased cumulus activity that can eventually become an area of thunderstorm formation and associated low-level boundaries left behind can themselves cause convergence and vorticity that can increase the level of organization and intensity of any storms that do form. An MCV that moves into tropical waters, such as the Gulf of Mexico, can serve as the nucleus for a tropical storm or hurricane. MCVs, like mesovortices, often cause an intensification of convective downburst winds and can lead to tornadogenesis. One form of MCV is the "comma head" of a line echo wave pattern (LEWP).

On Friday, May 8, 2009, a major MCV controversially dubbed an "inland hurricane" by local media moved through southern Missouri, southern Illinois, western Kentucky, and southwestern Indiana, killing at least 6 and injuring dozens more. Damage estimates were in the hundreds of millions. Top speeds of 106 mph (171 km/h) were reported in Carbondale, Illinois.

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