Meaning of FILLING in English
Used in describing the history of a low pressure system or an area of cyclonic circulation, it means an increase in the central pressure of the system. Although it usually describes the action of a pressure system on a constant pressure chart, it also means a surface low is decreasing in cyclonic circulation and losing its characteristics. The opposite of deepening.
Weather and meteorology English vocabulary. Английский словарь погоды и метеорологии . 2012