The mathematics that needs to be solved to produce weather forecasts isn't embarrassingly parallel in the way something like Ray tracing is or in the way the BO

The mathematics that needs to be solved to produce weather forecasts isn't embarrassingly parallel in the way something like Ray tracing is or in the way the BOINC projects like Folding@Home take advantage of. The mathematics involved is attempting to model the continually interacting, global state of weather across the planet in order to determine what it will be like at various places on the planet. These models are extremely reliant on being able to "share" data between parallel operations, if computer core 1 is doing a grid cell, and computer core 2 is calculating things about a neighbouring grid cell, it will need to know things about the grid cell core 1 is working on. These models run on supercomputers in order to facilitate efficient parallel processing in an environment where each node can access the memory of surrounding nodes since promptly accessing such memory is necessary for the models to be computed "faster than real time".