Two types of multi-sensor, real-time, 4km, hourly/6-hourly national precipitation analyses are produced in NCEP and archived at NCAR as part of the GEWEX/GAPP effort: the more timely NCEP Stage II, produced directly from the real-time gauge and WSR-88D radar data received at NCEP, and the NCEP Stage IV, which is a mosaic of regional multi-sensor analyses produced by the RFCs and benefits from the RFCs' manual quality control step.

The "Stage II" analysis was first developed in NCEP in coöperation with OHD in 1995-1996 (Baldwin, 1996). Each hour's analysis is performed three times: the "early" version merges radar data with hourly gauge reports in the METAR data, and is available at 35 minutes after the top of the hour; the analysis is then re-run 6-hours and 18-hours later, using the radar data and the HADS automated hourly gauge observations transmitted through the GOES Data Collection Platform.

The "Stage IV" analysis uses the hourly/6-hourly analyses transmitted from the 12 ConUS RFCs to NCEP through out the day. Each RFC typically performs each hour's analysis twice (an early, automated analysis, and a later, manually QC'd analysis) and sends out 4-6 batches of data to NCEP each day, and the receipt time at NCEP ranges roughly from within the hour to 12 hours after. The Stage IV mosaic for each hour/6-hour period is updated hourly to include any newly-arrived regional analysis.

These analyses are used at NCEP as input for precipitation assimilation in the Eta model, as part of the forcing for the land surface model, and as verifying analyses in precipitation forecast verification. Other applications, on-going and planned developments for the analyses will be discussed at the AMS meeting.