Edit: Just got another idea
Give me a key too for windspeed and Timmy will get the possibility to
get windspeed from mph to Beaufort / kmh in TodayPlus V011
Too much ??? 
@uk_skinner: Did you see my edited post ? Can you make that possible ?
Edit: Just a second idea: Get the value from numcities of the registry in your exe
and then create as many keys as you have cities to get
winddir / windspeed from every city.
@Timmy: When you make your grafics for windspeed, you should name
the grafic like the values of the var's. F.ex. NEE=144 --> 144.bmp
Then it is really easy to get the grafik with less code.

Example:
load,city,%var0%
calcvar,var4,fromconfig,winddir%var0%
image,0,0,%var4%.bmp,t
Hope, that works
Greetings Broesel