Plain English Meaning
The air pressure at the reporting station has been dropping fast, and it is still dropping when the report is made.
Full Definition
A METAR remark indicating that the station's atmospheric pressure is falling at a rate that meets the criteria for rapid change, typically a drop of at least 0.06 inches of mercury within the past hour, with the pressure still decreasing at the time of observation.
Context Anchor
Seen in the remarks section of an aviation routine weather report, especially when weather conditions may be changing quickly.
Derivation
A contraction of the words 'pressure' and 'falling rapidly,' shortened to fit the compact format used in METAR reports.
Why Pilots Care
Signals an approaching that may bring , , or reduced .