Microburst

Microburst is a small-scale, intense downdraft that, upon reaching the surface, spreads outward in all directions producing strong divergent winds. Microbursts are typically less than 4 km in diameter and last 5–15 minutes, but can produce wind speed changes of 30–45 knots — enough to cause a fatal loss of performance during takeoff or landing.

Wet microbursts: accompanied by heavy precipitation
Dry microbursts: occur with little or no rain reaching the surface
Major factor in several fatal accidents before wind shear detection systems were developed
LLWAS (Low Level Windshear Alert System) and TDWR (Terminal Doppler Weather Radar) help detect them