I've been fooling around with the weather generator in game. I just discovered a way to not take such a bad fps hit, while using the thunder option. By experimenting with the various size dimensions, you could have a series of different weather generators along your route. You could also control its length and width of each generator that you place. Basically you place the generator, you enter your numbers, white lines then appear on fmb map. While the generator is selected, you press the num pad 9 to have the cloud front rotate to your liking. Changing the values will control length and width. Its kind of a narrow cloud line, but that does help the fps quite a bit.
