What is an unscheduled weather advisory issued for ATC use to alert pilots of existing or anticipated adverse weather conditions with the next 2 hours ?

• A. PIREP
• B. SIGMET
• C. HIWAS
• D. CWA

Answer: (D)

Center Weather Advisory is the unscheduled weather advisory used by ATC to alert pilots of existing or anticipated adverse weather within the next two hours. It fills a specific need when weather poses potential hazards but doesn’t meet the formal criteria for a SIGMET or when a more immediate, operational alert is required for coordination between controllers and pilots. This advisory is designed to be timely and concise, focusing on the area, the type of weather, and the expected evolution over the two-hour window so pilots can plan routes and ATC can adjust traffic flow as needed.

Pilots’ PIREPs describe actual observed conditions from the cockpit, not an ATC-issued alert about forecast or developing weather. HIWAS is a continuous broadcast service that relays various weather advisories, not a single, situationally issued alert for a specific two-hour period. SIGMETs are formal warnings for significant weather hazards that meet defined criteria and cover longer ranges or more severe phenomena; CWAs target shorter, immediate, operational needs within a two-hour horizon.