Microburst

A Microburst is a downdraft that moves in a way opposite to a tornado. It is found in thunder storms. And it can be dangerous to an aircraft.
The typical microburst has an average duration of about 15 minutes from the time it is detected until it disappears, its divergence in the first 7 minutes is when it reaches a maximum in wind intensity; the descent occurs below the base of the storm or very close to it, and may have a radius of descent in the first minutes after it hits the ground from about 500 m.