It's a very good idea

but why don't you add a script foryour storm like Allan wake ?

It looks impressive but I don't think it's difficult ...

See If you make all the part of your level with model created in few part ( not much just roof door and the bulding in for or five part)

add a storm script like if a model come near than ... quants make the storm movement... Add some particule and sprite to make the dust and it's done.

I a long process to coordonate everything but I think It could be neccessary and important for your game cause storm look far away.

If you don't want to make the building fall in part cause the FPS slow down the idea could be adapt if you remove piece of the landscape and add some particule to hide the object.

anyway your project looks great And I wonder if anyone could help you with your project.

I'm not a programmer but If you want a car I could model it ... I'm working on lightwave and It's not very difficult to create one.

cheers