We have been evaluating the forecasts from the two cores by computing kinetic energy spectra and by examining the fine-scale structure in the solutions. The spectra in the two models differ substantially in the mesoscale. The WRF-ARW forecast spectra clearly show the observed transition from a wavenumber (k) dependence of k**(-3) at large scales to k**(-5/3) in the mesoscale at all levels in the free troposphere and lower stratosphere. Conversely, the WRF-NMM spectra exhibit only a subtle transition in the lower troposphere and a k**(-3) spectra (i.e., no transition) in the upper troposphere. These and other differences in the spectra reflect notable differences in the forecast fields and arise primarily from differences in the dynamical core dissipation and filtering formulations and configurations. We will present these spectra and forecast field examples, and we will outline the formulation and configuration choices that produce these differences in addition to discussing the implications of these forecasts experiment results for high-resolution winter season NWP.