Agree, this is a big player I believe. I don't know a whole heck of a lot about the basic blueprints of forecast models (the math/physics, different schemes...I'm hoping that may actually be covered in my advanced forecasting class) but I do know this
Data assimilation and being able to properly and accurately parameterize are detrimental to the success and accuracy of a forecast model. This is what made the euro superior for all those years, the euro had superior assimilation and parameterization. This is exactly why I am not sold on AI yet. We need to drastically improve these capabilities and this is where (hopefully) quantum computing is going to come a long ways.