A reason (beyond hardware limits) math cannot model weather?

Is the only reason that math cannot model weather far in advance (among other things such as boiling water patterns) because it would require too much computational power? Or is there more to it? Is weather, et al too "organic" and thus math is not applicable to it?

This is much harder than predicting the stock market exactly, which is already proven to be impossible because even that's too stochastic. I think there are mathematical limits (chaos theory) that prevent predicting weather to ever be possible, regardless of technology.