You can easily build weather files to suite your needs.
The Cloud Editor
You will need a background upon which to build your cloud fronts. This can be any 256 color aka indexed color bitmap that’s 1024 x 1024. It can be all blue, yellow etc but it’s far more useful if it shows a map of your target terrain as a guide to placing cloud formations in more useful locations. So before you begin you will need a 1024 x 1024 bitmap representation of the terrain. I suggest grabbing a screen shot of the CBM in-game. This map doesn’t need to be accurate but it should show the entire CBM. Crop your image to show only the map, then scale the map to 1024 x 1024 pixels, and save it as 256 color aka indexed color. Strat Maps are not good for use with the Cloud Editor.
When you initially open the Cloud Editor, you’re presented with a blank white editing window with four letters, these are the anchors for the cloud front much like the anchors for a rectangle in a drawing program; here is the meaning to the four letters:
V Vector The line AV represents the vector, the path the cloud front will travel
A Anchor The line AW is the width of the cloud area
W Width The line WD represents the depth of the cloud area
D Depth
Using the File menu, open your terrain’s bitmap. The bitmap you made.
Among the tool buttons on the left, at the bottom is a button to Animate the cloud fronts. Click it to see a visual demonstration of the cloud editor in action. The editing buttons and text boxes won’t be usable while the animation is running.
Before you can move one of the anchors, A,V,W or D, you must select it’s corresponding button among the tools buttons on the left.
Experiment with the anchors, making a bigger cloud front, changing the directions etc. Try adding a zero to each of the text fields in Min Size FT and Max Size FT. The individual clouds will become much bigger and potentially more useful.
Within a few minutes you will be comfortable with using the Cloud Editor.
The concept of multiple fronts is very important. In the upper right corner of the tools section, click New to add a new cloud front and use the selection list above it to choose which front is active. Creating identical cloud fronts on top of each other with different start times can create a permanent standing cloud front in-game.
Your first serviceable weather file can easily be created in a weekend and you will get better with practice and experimentation.
It's been a couple of years since I was a regular user of the Cloud Editor, but I recall a known bug that prevented cloud front 1 from being drawn in-game. I suggest starting your cloud project with cloud front 2. You can always edit cloud front 1 if you find that it's active in-game.
There is a limit of 999 clouds. Increase cloud size and spread them out to achieve good results within the maximum cloud count. Also use the layer cloud type, and experiment with the Transparency setting
Use the AH Wiki for more information on specific functions, especially cloud types.
