forecast circle; forecast center position
Technical term in meteorology, especially for typhoon track forecasts. Refers to the circle indicating the probable center position of a storm at a given time.
The typhoon's forecast circle gets larger over time.
The Japan Meteorological Agency released the latest forecast circle.
進路予報 is the track forecast (the predicted path), while 予報円 is the circle representing the uncertainty of the center position along that path.
Compound of 予報 (forecast) and 円 (circle).