A squall line is defined as a row of severe thunderstorms that can develop along a warm or cold front. This type of weather phenomenon is characterized by a line of convective thunderstorms that can produce heavy rain, strong winds, hail, and sometimes tornadoes. Squall lines typically form in conditions that involve significant atmospheric instability and can travel long distances, often leading to severe weather conditions for areas they pass through.
The defining feature of a squall line is its organized structure that consists of multiple thunderstorm cells arranged in a line, which distinguishes it from other types of thunderstorms or rain events. Unlike slow-moving thunderstorms, which can produce heavy rain over a smaller area, squall lines can cause widespread impacts, often forming ahead of cold fronts and bringing abrupt changes in weather. This formation makes them an essential aspect of severe weather forecasting and understanding meteorological phenomena related to storm development.