A squall is a sudden, sharp increase in wind speed which is usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to an increase in the sustained winds over a short time interval, as there may be higher gusts during a squall event. They usually occur in a region of strong mid-level height falls,[clarify] or mid-level tropospheric cooling, which force strong localized upward motions at the leading edge of the region of cooling, which then enhances local downward motions just in its wake.
The word appears to be Nordic in origin, but its etymology is considered obscure. It probably has its roots in the word skvala an Old Norse word meaning literally, to squeal. The first known use of the term on surface weather analyses was in the United States in the late Nineteenth Century on U. S. Signal Corp Maps, begun in 1871.
