The answer to this question depends upon whether you will be executing the WRF EMS for research or real-time forecasting purposes. For real-time use, you need as much computer power as you can afford, with a premium placed on fast multi-CPU linux systems with at least 2GB of physical memory. That's just the nature of NWP as chances are that you will always want to run the model at higher resolutions over a larger computational domain with the most accurate (and expensive) physics and dynamics. For research purposes you will still want all the best for your runs; however, you will not need to make as many compromises as speed of the machine is not as critical of an issue since you are not up against any dead lines to get the model forecast completed.

You can use just about any linux workstation to run the WRF EMS, although the suggested minimum amount of physical memory is 512mb. The results of benchmark runs with both the NMM and ARW cores should provide some guidance in determining what type of performance to expect from your system relative to others.

The ARW core benchmark results are available.

The NMM core benchmark results are available.