I used the mission editor that has the options in a menu,
Open the editor and choose a option then save the mission, open the file with the text editor, and you can see the changes of the numbers. is easy
i open a training mission but the campaign use the same values i think
i´ts only see the relation .... the choosed option vs the changes in the text file.
i think that the game save the actual state of the weather, when you reload a savegame the weather is the same when you save it, but the counter timer resets to 0, and its needs some time to randomize again.
I don´t know if saving the game affects to the timer