About Radar Coded Message Composite Image with Tops

The display is an image representation of the Nexrad radar reflectivity graphical overlays of the cloud tops and valid Convective SIGMET forecasts. The display is intended to show a national summary of convective activity as related to aviation operations. The Nexrad Radar Coded Message (RCM) product originates as an automated text message generated at each NWS radar site and transmitted over the AFOS communications network. The RCM reflectivity data has spatial resolution of about 12 km and is updated every 30 minutes. The RCM was intended as a replacement for the Manually Digitized Radar (MDR) product which has been used for years as the input to the NWS Radar Summary graphic available over fax and other circuits. The raw RCM has considerable false echoes, so it is edited hourly by the Aviation Weather Center (AWC) before being formatted as an MDR in the autoROB product transmitted over AFOS. The autoROB is now used as the input for the NWS Radar Summary chart. The editing of the RCM at the AWC is an automated process that checks the RCM for meteorological validity when compared to current satellite images, synoptic conditions, neighboring radar sites, and lightning.

The displayed image is the edited reflectivity. The RCM includes the max top for each radar's area of coverage. The other tops shown on the display are derived from the satellite images at the centers of convective activity. Movements shown are the radar centroid movements as generated by the Nexrad processor.

The images are updated twice hourly and are posted at HH:35 and HH:55.