Surface data is crucial for mesoscale weather forecasting because its time and space resolution is unmatched among in situ observations. The Mesoscale Analysis and Prediction System (MAPS) and the Rapid Update Cycle (RUC) Surface Assimilation Systems (MSAS/RSAS) exploit the resolution of surface data by providing timely and detailed surface analyses. RSAS (also known as the RUC Surface or "RUCS" system) runs operationally at the NWS's National Centers for Environmental Prediction (NCEP). MSAS runs operationally at NWS Forecast Offices as part of the AWIPS workstation, and contributes quality control information to the Quality Control and Monitoring System (QCMS).

RSAS also runs quasi-operationally in the ESRL/GSD Central Facility. The ESRL/GSD RSAS is also used to quality control surface observations distributed through the Meteorological Assimiliation Data Ingest System (MADIS), and as the development system where new advances can be incorporated before being put into operations at NCEP. Grids from the ESRL/GSD RSAS are also made available via MADIS to interested parties in real-time by ftp, LDM, or OPenDAP. For a list of the analyzed and derived grids, see the Surface Analysis Description link below.


Data Access

MADIS subscribers can receive the real-time ESRL/GSD RSAS grids by requesting an ftp, LDM, or OPeNDAP account. In general, users who require a continuous datafeed will get better performance by accessing the data via ftp or LDM. All of the analyzed and derived grids are output in a single netCDF file, and we provide software that can be used to read the file and output the desired grids in a simple text format that can then be read in by your application.

Data Schedule

Grids valid at the top of the hour are updated every 15 minutes to incorporate newly arriving observations. The exact schedule of when the grids are available is difficult to predict, because of the varying and ever-increasing volume of observations being handled by the system. Therefore, LDM is the best method to receive the data. For those wishing to use ftp or OPeNDAP, however, here are the range of times when the RSAS grids were available on March 3, 2005:

Update Cycle    Available at Minutes Past the Hour
1    22 - 25
2    35 - 40
3    52 - 54
4    66 - 71

Real-time Graphics


Animated GIFs are available to loop the latest 8 hours of surface analysis grids. Single GIF images are also available for the grids from the current hour.


MSAS/RSAS Production Error Reporting

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Last updated 10 December 2007.