Xbox Guide -
At the main menu click on the world map, go over to any airport and click on the target symbol and click Set As Arrival and then click fly in the yellow box bottom right. After the loading screen press Ready To Fly in the yellow box bottom right.
Once flying if your top menu isn't on the screen press in your left stick to bring it up. Once you have it on screen move your curser over the cloud on the menu and press on it to bring up the weather options, move your curser over the lightening percentages setting and then push your Right Analog to the right to increase the percentage and you will get your achievement. (ACHIEVEMENT UNLOCKED)
You can close this weather menu and any other sub menu you open by pressing the small x at the top right and you can gain control of your plane again by closing the top menu by pressing in the Left Analog Stick.
Video Guide -