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ordinary cell thunderstorms

A thunderstorm produced by local convection within a conditionally unstable air mass

cumulus stage

the initial stage in the development of an ordinary cell thunderstorm in which rising, warm, humid air develops into a cumulus cloud

mature stage

the second stage in the three-stage cycle of an ordinary thunderstorm

dissipating stage

the final stage in the development of an ordinary cell thunderstorm when downdrafts exist through-out the cumulonimbus cloud

multicell thunderstorm

thunderstorms often in a line, each of which may be in a different stage of its life cycle

overshooting top

a situation in a mature thunderstorm when rising air, associated with strong convection, penetrates into a stable layer, forcing the upper part if the cloud to rise above its relatively flat top

gust front

a boundary that separates a cold downdraft of a thunderstorm from warm, humid surface air.

straight-line winds

strong winds created by a thunderstorms downdraft that flows outward, away from the storm in a straight line, more or less parallel to the ground

shelf cloud

a dense, arch-shaped, ominous-looking cloud that often forms along the leading edge of a thunderstorm's gust front, especially when stable air rises up and over cooler air at the surface

roll cloud

a dense, roll-shaped, elongated cloud that appears to slowly spin about a horizontal axis behind that leading edge of a thunderstorm's gust

outflow boundary

a surface boundary separating cooler more-dense air from warmer less-dense air.

downburst

A severe localized downdraft that can be experienced beneath a severe thunderstorm

microburst

a strong localized downdraft less than 4km wide that occurs beneath thunderstorms

heat burst

a sudden increase in surface air temperature often accompanied by extreme drying

squall line

a line of thunderstorms that from along a cold from or out ahead of it

bow echo

a line of thunderstorms on a radar screen that appears in the shape of a bow

derecho

strong, damaging, straight-line winds associated with a cluster of severe thunderstorms that most often form in the evening or at night

Mesoscale Convective Complexes

a large organized convective weather system comprised of a number of individual thunderstorms

supercell

a severe thunderstorm that consists primarily of a single rotating updraft

mesocyclone

a vertical column of cyclonically rotating air within a supercell thunderstorm

wall cloud

an area of rotating clouds that extends beneath a supercell thunderstorm and from which a funnel cloud may appear

flash floods

a flood that rises and falls quite rapidly with little or no advance warning, usually as the result of intenserainfall over a relatively small area

lightning

a visible electrical discharge produced by thunderstorms

thunder

the sound due to rapidly expanding gases along the channel of a lightning discharge

sonic boom

a loud explosive-like sound caused by a shock wave emanating from an aircraft traveling at or above the speed of sound

stepped leader

an initial discharge of electrons that proceeds intermittently toward the ground in a series of steps in a cloud-to-ground lightning stroke

return stroke

the luminous lightning stroke that propagates upward from the earth to the base of a cloud

dart leader

the discharge of electrons that proceeds intermittenly toward the ground along the same ionized channel taken by the initial lightning stroke

dry lightning

lightning that occurs with thunderstorms that produce little, if any, appreciable precipitation that reaches the surface

heat lightning

distant lightning that illuminates the sky but is too far away for its thunder to be heard

Saint Elmo's Fire

a bright electric discharge that is projected from objects when they are in a strong electric field, suchas during a thunderstorm

tornado

an intense, rotating column of air that often protrudes from a cumuliform cloud in the shape of a funnel or a rope whose circulation is present on the ground

funnel cloud

a tornado whose circulation has not reached the ground

tornado alley

a region in the great plains of the US extending from Texas and OK northward into Kansas and Nebraska where tornadoes are most frequent

suction vortices

small, rapidly rotating whirls perhaps 10m in diameter that are found within large tornadoes

tornado watch

a forecast issued to alert the public that tornadoes may develop within a specified area

tornado warning

a warning issued when a tornado has actually been observed either visually or on a radar screen

Fujita scale

a scale developed by T Theodore Fujita for classifying tornadoes according to the damage they cause and their rotational wind speed

Enhanced Fujita Scale

a modification of the original fujita scale that describes tornado intensity by observing damage caused by the tornado

tornado outbreak

a series of tornadoes that forms within a particular region- a region that may include several states

supercell tornadoes

tornadoes that occur within supercell thunderstorms that contain well-developed, mid-level mesocyclones

hook echo

the shape of an echo on a doppler radar screen that indicates the possible presence of a tornado

nonsupercell tornadoes

a tornado that occurs with a cloud tha tis often in its growing stage, and one that does not contain a mid-level mesocyclone, or wall cloud

gustnadoes

a relatively weak tornado associated with a thunderstorms outflow

landspout

relatively weak nonsupercell tornado that originateswith a cumiliform cloud in its growth stage and with a cloud that does not contain a mid-level mesocyclone

NEXRAD

an acronym for next generation weather radar

waterspout

a column of rotating wind over water that has characteristics of a dust devil and tornados

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