Plain English Meaning
If you are flying and need to know the weather ahead, you can call Flight Service on the radio and a specialist will give you up-to-date weather for your route.
Full Definition
Weather information provided to pilots by Flight Service while they are airborne, delivered by radio on request. The service includes current conditions, forecasts, hazardous weather advisories, pilot reports (PIREPs), and updates relevant to the route of flight, allowing pilots to make decisions in the air based on the latest information.
Context Anchor
A pilot uses this when contacting Flight Service after departure, especially if clouds, , , storms, or the destination weather are changing.