From the RUC to the Rapid Refresh

The Rapid Update Cycle (RUC) is evolving into a new 1-h update cycle configuration using a version of the WRF model over a North American domain, to be called the Rapid Refresh. The Rapid Refresh (RR) is to be implemented in 2007, but has been undergoing preliminary testing from 2003-2005 with twice-daily real-time testing of the WRF-ARW model using RUC initial conditions, called the ‘WRF-RUC'.

The Rapid Refresh domain is about 2.6x larger than the RUC CONUS domain, expanding to coverage of Alaska, Puerto Rico, the Caribbean, and most of Canada. The horizontal resolution will be about 13 km, the same as the 13-km RUC implemented at NCEP in early summer 2005.

While the RR will use a version of the WRF model, its physical parameterizations will be similar to those used successfully with the RUC, including the mixed-phase cloud microphysics parameterization developed largely by NCAR for improved depiction of supercooled liquid water. The Rapid Refresh, like the RUC, will continue hourly cycling of full 3-d hydrometeor fields correcting previous 1-h forecasts with satellite cloud and METAR cloud observations. The Rapid Refresh is planned to use the NCEP/EMC Gridpoint Statistical Interpolation (GSI, described in more detailed in a companion paper by Devenyi et al.) including RUC-designed enhancements for use of surface data and cloud data. This paper will described the Rapid Refresh configuration, plans, and initial development and testing as of the conference date.