What is a "squall line"?

A squall line refers to a narrow band of severe thunderstorms that typically develops along or ahead of a cold front. This phenomenon is characterized by a quick and significant increase in wind speed (squall) and often produces severe weather conditions such as heavy rain, strong winds, hail, and even tornadoes. The alignment of these thunderstorms in a line provides a clear indication of the dynamic weather typically associated with cold fronts.

In contrast to other weather formations, a squall line specifically indicates active and severe weather. While a line of steady rain associated with warm fronts might occur, it does not exhibit the same characteristics as squall lines, which are heavily influenced by the instability and lifting associated with cold fronts. Additionally, calm winds or formations of clouds indicative of fair weather would not apply to the definition of a squall line, as those do not reflect the turbulent and dramatic conditions present in squall lines.