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squall line[′skwȯl ‚līn]
A line of thunderstorms near whose advancing edge squalls occur along an extensive front; the region of thunderstorms is typically 12 to 30 miles (20 to 50 kilometers) wide and a few hundred to 1200 miles (2000 kilometers) long.
A narrow zone of meteorological activity usually parallel or nearly parallel to a cold frontal surface, occurring some distance away. Squall-line activity, or a line squall, is characterized by thunderstorms, heavy rain, brief wind shifts, gusty winds, abrupt pressure rises, and abrupt temperature falls.