The Rapid Update Cycle in the U.S. continues to be the only 1-h assimilation and mesoscale forecast cycle in the world running operationally as part of an operational numerical prediction center (U.S. National Centers for Environmental Prediction - NCEP). Predictions from the RUC are used heavily as mesoscale guidance for short-range forecasts, especially for aviation, severe-weather forecasting and situational awareness. An effective assimilation technique for 3-d radar reflectivity has been developed and being used successfully by specifying latent heating and moistening in a pre-forecast diabatic digital filter initialization (DDFI) within the RUC model (summary in this paper, more detail in paper by Weygandt and Benjamin). The RUC update will also include use of the RRTM longwave radiation, improving RUC diurnal cycle behavior.
The Rapid Refresh version of the WRF model is in testing with partial RUC-like physics (NCAR-Thompson microphysics, Grell-Devenyi convection, Mellor-Yamada-Janjic PBL, RRTM longwave radiation) with both ARW and NMM dynamic cores. It is being cycled using the Gridpoint Statistical Interpolation (GSI) assimilation over the North American domain, 2.6 times larger than the RUC domain. Current testing results will be presented.