Comment by PolarizedPoutin

It's a good question! It's true that the output is massive, I believe ~9 petabytes and growing. But running the model is super expensive. It runs on ECMWF's supercomputer. Not sure how many cores but I would guesstimate in the 10k - 100k core range just for one instance. So computing the data on the fly is super expensive, probably much more expensive than just storing it.