1. Go to the Full Mission Builder (FMB).
2. Open an existing mission or start a new mission.
3. In the menu at the top, select 'VIEW' then 'OBJECT BROWSER'
4. In the object browser window, on the type tab, click the down-arrow for the object type (the first entry at the top o the window).
5. Select the 'LOCAL WEATHER' object from the items.
6. Position your cursor on the map & press 'control-left mouse click' where you want to place the centre of your weather front. A small cloud icon will appear on the map.
7. In the "OBJECT BROWSER' window, select the 'CONFIGURATION' tab.
8. You should see six configurable items on the 'CONFIGURATION' tab:

* Name: You can change the name of the weather front if you like.
* Ra: This is the radius of the weather front along the 'a' axis. Change the number to increase the size of the front area. As you do so, you'll see a dotted line appear in an area around the cloud icon. This is the area for the weather front.
* Rb: This is the radius of the weather front along the 'b' axis. Change the number to increase the size of the front area. As you do so, you'll see a dotted line appear in an area around the cloud icon. This is the area for the weather front.
* H: This is the height (in metres) of the weather front.
* Rain: A tick box to turn rain off/on, but it's not working.
* Dynamic: A tick box to make your weatherf ront dyanamic. I have mine weather fronts dynamic-ticked.

You can also press your 7, 9, 3, 1 numpad keys to roate the front how you like. I prefer an eliptical front that's rather narrow but very wide.

9. Click on the 'PROPERTIES' tab. You'll see a number of slider to adjust various values, but the GUI is broken. You can still enter numbers in the boxes on the right of each slider, but it's best to manually edit your mission file to enter these values.
10. Take note of the wind direction you've set in the 'VIEW'-'MISSION PARAMETERS'-'WIND FLOW TAB'. This will be the direction the front moves over time.
11. Save your mission.
12. Open your mission file in notepad or a text editor.
13. At the bottom the file, find the [WeatherFront] section. It will probably have a line immediately underneath saying something like...

LocalWeather_0 THUNDER_GEN 100000 50000 165660.18 261920.10 13000 30

... Change the word Thunder_Gen to one of these:

CUMULUS_GEN
OVERCAST_GEN
THUNDER_GEN
14. Below the weatherf ront info, you find another section heade dsomething like [LocalWeather_0] ...
with a series of parameters:

EllipticA 100000 ................ This is the Ra parameter.
EllipticB 50000 ................. This is the Rb parameter.
RotAngle 0 ....................... This is a rotation verctor for how you rotated the front in FMB.
ShiftX 0 ........................... Unknown.
ShiftY 0 ........................... Unknown.
BaseHeight 1000 .............. This is the lower cloud base height. Adjust as desired.
IsRain 1 .......................... Turns rain off/on. Not working.
IsDynamicEnabled 1 .......... Dynamic = 1
ParticipType 1 .................. I adjust with values from 1 to 3.
DropSize 0 ....................... Values 1 - 10 seems to affect cloud transparency.
RainPower 0 ..................... Unknown. Probably not used.
ThermalIntensity 5 ........... Values 1 - 10. How intense the updrafts are.
CloudsDensity 5 ................ Values 1 - 10. How dense clouds are.
MidSize 5 ......................... Values 1 -10. Seems to affect how 'bunched' clouds are.

After editing, save your text file.