Definition
RWDS (Radar Weather Data System) is an FAA system that collects weather radar information from ground-based weather radar sites and distributes it to air traffic control facilities for use in advising pilots of significant weather. The acronym is treated as identical to RRWDS (Radar Remote Weather Display System); both refer to the same operational data feed used by controllers.
Plain English
RWDS is the system that pipes weather radar pictures from radar sites on the ground to air traffic control, so controllers can see storms and pass that information to pilots. It means the same thing as RRWDS in FAA documents.
Context Anchor
You may see RWDS in an airport notice when runway distance signs are missing, damaged, out of service, or otherwise affected.
Derivation
Each letter stands for a part of the system's job: 'Radar' (the sensor), 'Weather' (what it watches), 'Data' (what it sends), 'System' (how it's delivered). RRWDS adds 'Remote Display' to emphasize that the radar picture is shown at a location away from the radar itself.
Why Pilots Care
Gives pilots real-time awareness of weather hazards ahead without needing on-site radar equipment.
Grounding Statement
A runway remaining distance sign with the number 4 means about 4,000 feet of runway remains from that point.
Intuition Check
Do not read RWDS as a different system from RRWDS here. In this FAA entry, RWDS means the same thing as RRWDS: runway remaining distance signs.
Example Sentence 1
The controller's advisory about a line of heavy precipitation thirty miles ahead came from RWDS data feeding their display.
Example Sentence 2
Controllers use the RWDS to monitor weather patterns over a wide area from a central location.