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The Real Time Mesoscale Analysis with Rapid Updates (RTMA-RU) extends the hourly RTMA to a framework that provides analyses
every 15 minutes on a 2.5 km CONUS grid having a product latency of 15-20 minutes. Analysis fields include surface pressure, 2 m temperature,
2 m moisture, 10 m wind speed and direction, 10 m wind components, 10 m wind gust, cloud ceiling, and visibility. The background field
used in the RTMA-RU data assimilation algorithm comes from the 15 minute output available from the hourly updated,
3 km High Resolution Rapid Refresh (HRRR) system.
Special attention is given to the ceiling and visibility analysis components in support of the aviation weather community.
The observation selection algorithm of the original RTMA was modified to select only one observation per site - more specifically, the one
closest to the analysis time. This adjustment allows for a closer fit to observations in each analysis as well as the improved use of of
special (SPECI) reports. SPECI reports are typically associated with flight-impacting weather systems and are generated on a sub-hourly basis,
in addition to the regular hourly METAR reports. While these SPECI reports are not particularly numerous, they are important to ensure that the
RTMA-RU reflects the current weather conditions. The modified algorithm ensures the SPECIs always get the strongest weight in the analysis.
RTMA fields for regions of the CONUS are displayed on the
NCEP Model Analyses & Forecasts page.