Plain English Meaning

A weather report made by a pilot describing what they actually saw or felt while flying — bumps, ice, cloud tops, visibility, and so on — so other pilots and forecasters know what's really happening up there.

Full Definition

Reports of actual weather conditions encountered by a pilot in flight, transmitted to a ground facility (typically Flight Service) and disseminated to other pilots, controllers, and forecasters. PIREPs include items such as flight conditions, cloud layers, turbulence, icing, visibility, winds aloft, and any unexpected weather. They provide real-time, location-specific weather information that cannot be obtained from forecasts or alone.