| Abbreviation | Definition |
|---|---|
| R&D | Research and Development |
| RAA | Running Annual Average |
| RAFC | Regional Area Forecast Center |
| RAMDIS | RAMM Branch Advanced Meteorological Satellite Demonstration and Interpretation System |
| RAP | Reactive Atmosphere Process |
| RASS | Radio Acoustic Sounding System |
| RASS | Ranging And Sounding System |
| RAWB | Return Air Wet Bulb temperature at evaporation |
| RAWS | Remote Automatic Weather Station |
| RC | Reserve Component |
| RCA | Regular Countably Additive |
| RCH | Rockwell hardness test |
| RCL | Ranger Crestliner Lund |
| RD | Rising Darkness |
| RDA | Radar Data Aquisition |
| RDT | Rapid Developing Thunderstorm |
| RDTE | Research, Development, Test, and Evaluation |
| RFC | River Forecast Center |
| RFD | Rear Flank Downdraft |
| RFE | RainFall Estimation |