These verification statistics show that the hourly RUC assimilation cycle improves short-range forecasts (compared to longer-range forecasts valid at the same time) even down to the 1-h projection.

Verification of forecasts from the latest 20-km version is presented using rawinsonde and surface observations. This followed an initial implementation with 60-km horizontal grid spacing and a 3-h cycle in 1994 and a major upgrade including 40-km horizontal grid spacing in 1998. Herein, the RUC analysis framework in the hybrid coordinate is described, and some considerations for high-frequency cycling are discussed.Ī 20-km 50-level hourly version of the RUC was implemented into operations at NCEP in April 2002. The use of a quasi-isentropic coordinate for the analysis increment allows the influence of observations to be adaptively shaped by the potential temperature structure around the observation, while the hourly update cycle allows for a very current analysis and short-range forecast.

The Rapid Update Cycle (RUC), an operational regional analysis–forecast system among the suite of models at the National Centers for Environmental Prediction (NCEP), is distinctive in two primary aspects: its hourly assimilation cycle and its use of a hybrid isentropic–sigma vertical coordinate. Upper-air verification against rawinsondes Verification-Analysis and forecast fit to rawinsonde and surface observations Cloud/hydrometeor analysis using GOES cloud-top data Three-dimensional optimum interpolation analysis Unified analysis framework in a generalized vertical coordinate Observational data assimilated in the RUC and calculation of innovations

Operational configuration for the 20-km version of the RUC analysis 2) A demonstration of the cumulative effect of narrow analysis time windowing.1) The trade-off between spatial and temporal resolution.Design of the RUC 1-h assimilation–forecast cycle

Resolution by Tracy Lorraine