Severe Thunderstorm Watch- is issued when conditions in the Troposphere are favorable for Severe Thunderstorms.
Severe Thunderstorm Warning- is issued when a spotter or doppler radar indicate a strong thunderstorm,capable of producing large hail and/or damaging winds.
Tornado Watch- is issued when conditions in the Troposphere are favorable to Tornadic Development.
Tornado Warning- is issued when a spotter or doppler radar indicate a strong thunderstorm, capable of producing a tornado.
Tornado- A rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud.
Severe Thunderstorm- defined in the United States as having either tornadoes, gusts at least 58 mph, or hail at least 3/4 inch in diameter.
Flood- a great flowing or overflowing of water, esp. over land not usually submerged.
| Mesocyclone- a small cyclone that arises near a thunderstorm and is sometimes associated with the occurrence of tornadoes. |
Shelf Cloud/Gust Front- a term describing the characteristic radar return from a mesoscale convective system that is shaped like an archer’s bow. These systems can produce severe straight-line winds and occasionally tornados, causing major damage.
Derecho- a widespread and long-lived, violent convectively induced windstorm that is associated with a fast-moving band of severe thunderstorms usually taking the form of a bow echo. Derechos are usually not associated with a cold front, but a stationary front within a highly buoyant, warm airmass. A warm weather phenomenon, derechos occur mostly in summer, especially July (in the northern hemisphere), but can occur at any time of the year and occur as frequently at night as in the daylight hours.
Outflow Boundary- a storm-scale or mesoscale boundary separating thunderstorm-cooled air (outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature. Outflow boundaries may persist for 24 hours or more after the thunderstorms that generated them dissipate, and may travel hundreds of miles from their area of origin. New thunderstorms often develop along outflow boundaries, especially near the point of intersection with another boundary (cold front, dry line, another outflow boundary, etc.
Pileus Clouds- is a small, horizontal cloud that can appear above a cumulus or cumulonimbus cloud, giving the parent cloud a characteristic "hoodlike" appearance.
Hail- a form of precipitation which consists of balls or irregular lumps of ice (hailstones). Hail is a type of snow. Hailstones on Earth usually consist mostly of water ice and measure between 5 and 50 millimeters in diameter, with the larger stones coming from severe thunderstorms. Hail is only produced by cumulonimbi (thunderclouds), usually at the front of the storm system, and is composed of transparent ice or alternating layers of transparent and translucent ice at least 1 mm thick. Small hailstones are less than 5 mm in diameter, and are reported as SHGS. Unlike ice pellets, they are layered and can be irregular and clumped together.