A downburst is a strong downrush of air from a thunderstorm. It is also referred to as strong straight Line winds. Downburst wind speeds can be phenomenal, with 158 mph measured from a downburst at andrews air force base in maryland in 1986. As viewed from the air, downbursts have a damage pattern that gets wider along its path, as opposed to that of a tornado which exhibits a pattern that converges toward one central track. A small downburst, with a damage swath less than 2.5 miles across, is called a microburst. These are extremely dangerous to aviation. A large downburst is called a macroburst.
Strong downbursts will definitely cause roaring sounds and people may often refer to a Sound like a freight train, terms typically associated with tornadoes. Although downbursts are not tornadoes, they can cause damage equivalent to that of a small to medium tornado. After all, wind is wind.
A major downburst occurred late in the afternoon on may 21 1996 in Plymouth county in eastern Massachusetts. Earlier in the day, downbursts swept across southern portions of Hartford, Tolland and Windham counties in Connecticut with gusts to 70 mph reported and trees knocked down. But the storm that moved across Plymouth county had a measured gust to 104 mph in Whitman and caused 60 injuries in the City of Brockton and a total of about 4 million dollars in damage. Thousands of trees and tree limbs were blown down from northwest to southeast across a wide area, some striking homes and automobiles. Several thousand electric customers remained without power for several days. A number of cemeteries were severely damaged when large trees were uprooted.
Golf ball size hail accompanied this storm. When unusually large hail is present, you should always take immediate precautions because the storm could be capable of producing a downburst or even a tornado.