Where is the potential energy present before the tornado occurs?

Answer 1

The energy is stored in the air as thermal energy. A supercell thunderstorm turns that into kinetic energy in the form of rotating wind. Under the right conditions that rotation can form a tornado.

Answer 2

The potential energy before a tornado occurs is stored in the form of warm, moist air at the Earth's surface. This air has the potential to rise and release its energy as the storm system intensifies, leading to the formation of a tornado.