A lightning watch will be in effect 30 minutes prior to thunderstorms being within a ___ NM radius

• A. 5 NM
• B. 10 NM
• C. 15 NM
• D. 20 NM

Answer: (A)

Lightning watch is a safety alert that gives advance warning of approaching lightning hazards so personnel and operations can take protective actions. The watch is activated 30 minutes before thunderstorms are forecast to be within a small, defined radius around the area. The standard radius used is five nautical miles. This threshold provides enough lead time to secure vulnerable munitions, pause risky activities, and brief crews before lightning is likely to impact the area, while avoiding unnecessary disruption that would come with a larger radius. If the radius were much larger, the watch would be overly conservative and disruptive; if it were smaller, you wouldn’t have sufficient time to implement safety measures. Five nautical miles is the practical compromise for timely protection.