Definition
An indicator placed in a METAR or SPECI weather report to show that the report is a correction to a previously transmitted observation for the same time. It appears immediately after the report type or station identifier and signals that the data following has been amended to fix an error in the earlier transmission.
Plain English
A label on a weather report that means "this version replaces the one we sent before because we had to fix something in it."
Context Anchor
Seen near the beginning of a METAR, usually after the report type, when a previously issued weather report needed correction.
Derivation
From the Latin 'correctus,' meaning 'made right' or 'set straight.' In weather reporting, COR simply flags that the report has been put right after an earlier mistake.
Why Pilots Care
Pilots must notice COR to confirm they are using the latest and most accurate weather data for safe flight decisions.
Intuition Check
COR does not mean course or corridor here. In a METAR, it means the weather report was corrected after its first issue.
Example Sentence 1
The METAR showed COR after the station identifier, so the pilot knew this version replaced the earlier observation.
Example Sentence 2
After seeing COR in the report, the pilot checked the updated visibility and wind values.