A power flash is a flash of light caused by arcing electrical discharges from damaged electrical equipment, most often severed power lines. They are often caused by strong winds, especially those from tropical cyclones and tornadoes, and occasionally by intense downbursts and derechoes.
They can be distinguished from lightning by the fact that they originate at ground level, the blue color of the flash, and depending on distance, the sound of high-voltage lines shorting out.