violent thunder and fierce wind; rapidly changing situation; swift action
A yojijukugo originally describing a violent storm, now often used metaphorically for a situation that changes with great speed and intensity, or for taking swift, decisive action.
The market fluctuated like a violent thunderstorm.
His swift, decisive action saved the company.
Also a yojijukugo meaning 'with lightning speed'; 疾風迅雷 emphasizes extreme speed, while 迅雷風烈 emphasizes violent intensity and rapid change.
A yojijukugo combining 迅雷 (swift thunder) and 風烈 (fierce wind). The exact historical origin is uncertain, but it is used in classical Chinese-influenced Japanese to evoke a violent storm.