Severe thunderstorms can create incredible violence as they pass over an area. Among their most devastating aspects are downbursts. They can cause swaths of downed trees and power lines, and even structural damage, up to tens of miles wide.
A downburst is a severe localized wind blasting down from a thunderstorm. These strong downward currents are classified by meteorologists as microbursts if the downburst covers an area less than 2.5 miles in diameter and as macrobursts if the down burst covers an area of at least 2.5 miles in diameter.
Wind shear is any sudden change of speed or direction in wind flow. Microbursts have strong wind shear horizontally from their front to back edges and vertically from the surface to near cloud base.