A powerful and highly concentrated thunderstorm is called a micro-burst. Water falls at such a high rate of speed, and high volume, that it strikes the ground and splashes back up.

In the center of the storm is the downdraft, on the outer edge is the updraft. Between the two is the area of windshear.

A northern Wisconsin forest laid flat in 1977 by a microburst from the Independence Day storm. Photographed by Ted Fujita.

The gust front of a rapidly moving microburst cell during daylight hours is often visable. At night, in the dark, it is not. This has always posed a serious problem at airports because doppler radar does not always display the exact location of the cell. Air traffic controllers have difficulty trying to determine whether a the storm is nearby, far away, or directly over the airport.

Windshear cannot be detected directly, but the early stages of a newly developing or approaching thunderstorm can. When a thunderstorm is moving toward a barometric sensor, it will first present a gentle rise in atmospheric pressure, which is the outer rim of the storm. Scientists refer to this as the "gust front". As the center of the storm nears and passes the sensor it will then shift to a very noticeable area of low pressure.

In 1995 Kel Precision Atmospheric Instrumentation (PAI) developed the first ProRata enhanced high resolution barometer, capable of detecting moving thunderstorms, and also at the early stages when they begin to develop.

A Wild Season At The Monroe County Airport

Scenario Sensor Specifications

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