Microburst

A microburst is a small, intense downdraft produced by a thunderstorm. When the downdraft reaches the ground, the air spreads outward in all directions, creating a gusty outflow that can cause damaging winds over a relatively compact area. Microbursts are typically 2 to 4 kilometers in diameter and last from a few seconds to several minutes, making them distinct from larger downbursts known as macrobursts.

There are two main forms of microbursts. Wet microbursts involve heavy precipitation reaching the surface, while dry microbursts occur with little or no surface rain. Both arise from evaporative cooling and the entrainment of drier air into the descending air, which increases the negative buoyancy and accelerates the downdraft. Upon reaching the ground, the air diverges suddenly, producing strong, gusty winds and often a sharp wind direction change.

Detection and warning systems have improved the ability to identify microbursts. Doppler radar can reveal signatures of localized downdrafts and outflow boundaries, while terminal Doppler radar (TDWR) and other weather radar systems help detect gust fronts near airports. Ground-based wind sensors and alert networks monitor low-level wind shear to provide warnings for aviation operations.

Impact and safety considerations. Microbursts pose significant hazards to aircraft during takeoff and landing due to rapid changes in wind speed and direction. They can also cause ground damage, power outages, and injuries. Understanding their frequency, structure, and signatures supports forecasting, warning issuance, and risk reduction for aviation and outdoor activities.