Plain English Meaning

A short code in a weather report that changes or qualifies the meaning of what follows — telling you things like 'this report came from an automated station,' 'this report is a correction,' or 'this weather is light, heavy, or nearby rather than at the field.'

Full Definition

In a METAR or surface aviation weather observation, a modifier is a code element that qualifies the report itself or a weather group within it — indicating, for example, that the report is automated (AUTO), corrected (COR), or that a weather phenomenon is in the vicinity (VC), light (-), or heavy (+).

Context Anchor

Seen in coded aviation weather reports such as METARs, near the of the report after the time of observation.