What is a microburst?

A microburst is a concentrated column of rapidly sinking air descending from a thunderstorm, striking the surface and spreading horizontally in all directions. The area affected is small, generally under about 2.5 miles across, and the event is brief, typically lasting five to fifteen minutes, but the winds can exceed 100 miles per hour and cause damage easily mistaken for a tornado. The distinguishing evidence on the ground is the pattern: microburst damage radiates outward from a center, while tornado damage shows convergent, rotational patterns.

Two types occur. Wet microbursts arrive with heavy rain and are common in humid climates. Dry microbursts fall in arid regions where rain evaporates before reaching the ground, cooling the air and accelerating the descent while leaving almost no visible precipitation, which makes them dangerous precisely because there is little warning. A ring of blowing dust spreading outward is often the only visual cue.

The aviation history is why the phenomenon is well studied. An aircraft flying into a microburst first encounters a headwind that increases lift, then the downdraft, then a sudden tailwind that removes lift at low altitude, a sequence that caused several fatal crashes including Delta Flight 191 at Dallas-Fort Worth in 1985. Research led by meteorologist Ted Fujita identified the mechanism, and the response was systemic: Doppler radar wind shear detection at airports, onboard predictive wind shear systems, and mandatory pilot training in escape procedures. Fatal wind shear accidents in US commercial aviation have become rare as a result, which is one of the clearer cases of a meteorological discovery translating directly into lives saved.