In most cases, storm fronts that have the towering clouds and lightning are cold fronts. That's Cold air sliding along the ground and pushing existing calm air up and out of the way. As such, you usually get sudden gusts at low level first. So as suggested, you really need to look at ground features (trees, grass, flags ...) between you and the storm to see those gusts coming. The gusts are going to make it difficult because once they reach you, it's going to make getting your drone down and back a load of fun! For that reason, it could be best to be out of your vehicle and in touch with the weather ...
And great idea about the frame-grab to get the lightning from video by the way ...
Good comments. Thanks FoxhallGH
