An Initial RUC cloud analysis assimilating GOES cloud-top data

An initial cloud analysis for the RUC has been developed and refined since early 1999 and is planned for implementation later in 2000. This analysis performs both cloud clearing and cloud building, and uses the background hydrometeor (5 types) mixing ratio fields forecast explicitly in the RUC using the MM5 mixed-phase cloud microphysics. This technique will be described. Assimilation of the NESDIS GOES sounder-based cloud-top pressure data has been tested in a real-time parallel version of the RUC run at FSL. Positive effects on forecasts of cloud tops and precipitation have been demonstrated. In order to enhance the resolution and coverage of the sounder-based cloud product, a similar product based on the higher-resolution GOES imager data has been developed. The two products are compared for relative strengths and weaknesses regarding hourly assimilation into the RUC. Initial performance will be presented at the conference.