What does the abbreviation "RA" signify in a TAF?

The abbreviation "RA" in a TAF signifies rain. This code is part of the meteorological shorthand used in aviation weather reporting, where each letter or combination of letters represents specific weather phenomena. In TAFs, which are forecasts specifically for the area around an airport, "RA" indicates that rain is expected in the forecast period. Understanding these abbreviations is crucial for pilots and air traffic controllers to assess weather conditions that may affect flight operations, including visibility and runway conditions.

The other options do not accurately represent the standard weather abbreviations used in TAFs. Radar activity, for example, is not a term used in this context, nor are retired aircraft or relative altitude relevant to weather forecasting in aviation. Knowing these distinctions is key to interpreting TAFs effectively.