[stankypickle]

It is because there is an understanding, from first principles, of the dynamics that drive weather (e.g. conservation of mass, momentum and energy). The current models are build upon these principles to make predictions, and conform to expectations of how physics operates. The method that these models are based on (finite volume) is efficient and adaptable if modifications need to be made.

Using AI and ML to make predictions about weather will likely not account for the conservation principles and might lead to ridiculous results (in some sense). Creating an accurate AI/ML model of a complex and chaotic system might lead to wrong predictions under extreme circumstances (e.g. predicting the weather >5 days out for an extreme hurricane) or under conditions where some implicit assumption has changed. One can at-least attempt to grapple with these issues when using finite volume. Under AI/ML you just have to hope your model is properly trained.