Microburst

An intense, localized downdraft from a thunderstorm or rain shower that strikes the ground and spreads outward in all directions, creating a rapidly changing wind field within an area less than 2.5 miles in diameter. A microburst can produce headwind-to-tailwind shear of up to 45 knots within seconds, which can overwhelm the performance capability of any aircraft. On approach, a pilot first encounters an increasing headwind (higher airspeed), then a downdraft, then a tailwind (decreasing airspeed and loss of lift). Maximum intensity occurs within 5 minutes of ground contact and seldom lasts longer than 15 minutes.