line squall Stormy conditions, with sudden changes of wind and heavy cloud, often involving thunderstorms and a temperature fall, which are often associated with the passage of a cold front. The squall defines the line of the cloud and wind structure. Warm air is overrun by cold air to produce the squall line.

line squall Stormy conditions, with sudden changes of wind and with heavy cloud, often involving thunderstorms, and a temperature fall, often associated with the passage of a cold front; it defines the line of the cloud and wind structure. Warm air is overrun by cold air to produce the squall line.