Forecasting is a different problem. It usually involves developing a computerise model of meterological change over a terrotory from a huge range of data sets. For that you some really big beast of a computer system with huge data handling capability for land and sea based data gathering sensors along with data from satellites and radar. Forecasts are only useful if all the computations are done in time to be useful. Weather forecasting is the kind of problem, for which you need a supercomputer.
Weather forecasting in the UK is a national obsession. It comes from having an economy dependent on maritime trade routes and what the weather is likely to do to the ships at sea was and still is, a national strategic concern. A lot of money is spent on tracking the procession of weather systems coming across the Atlantic on the Jetstream and how it will affect the UK. Forecasts are done for squares of territory over 5 days, the latest models are down to 300m squares. Weather forecasting is big business, lots of industries need it.
They use a CrayXC40 16petaflop Supercomputer with 480,000 cpus for the 1.5km square weather forecast.:eek:
I expect the US has the same kind of thing for predicting the path of hurricanes.