The Rapid Update Cycle (RUC, Benjamin et al. 2004a,b), covering 2/3 of North America, continues to be the only 1-h (hourly updating) assimilation and mesoscale forecast cycle in the world running as part of an operational numerical prediction center (US National Centers for Environmental Prediction - NCEP). RUC prediction grids are used heavily as mesoscale guidance for short-range forecasts, especially for aviation, severe-weather, and situational awareness forecast users. In this report, we summarize both significant changes planned for a RUC upgrade at NCEP later in 2007 and testing and development toward the 2009-planned implementation of the Rapid Refresh (RR), an hourly update analysis/forecast cycle succeeding the RUC. The RR differs from the RUC in using a version of the Weather Research and Forecast (WRF) model and a version of the Gridpoint Statistical Interpolation (GSI) analysis (used at NCEP), both including RUC-unique enhancements, over an extended North American domain. These modifications and subsequent testing for both RUC changes and RR development are described in this paper.
This publication was presented at the following: