A persistent winter cold bias has been noted in the mesoscale Eta and NMM models run operationally at NCEP. This condition is most noticeable under clear-sky, weak wind conditions in the stable boundary layer at night where the surface energy budget often involves a balance between downward sensible heat flux, downward longwave radiation, and upward soil heat flux. To examine the cold bias, output from the models will be compared with data from various flux observing networks, with alternate model formulations tested, e.g. stable boundary layer and surface layer parameterizations, low-level clouds, and land-surface processes including snowpack.