You're right, actually the weather radar screen is the standard one: I did a lot of analysis to understand what data I do need to create a custom weather radar, what data is actually available and which kind of format, then I did some code simulations and all the results bring me to the very 'simple' conclusion that the amount of work to code a custom weather radar is huge to say the least, too huge for just one people with not too much time available (making the terrain radar is way simpler than making the weather radar).
But I can say one thing: that doesn't mean that there's no chance to have a custom weather radar, I'll create it after the release of our MD-82 and before to start to work to our next plane so it will be available as an update.