You have it backwards, ATIS doesn't pull from METARs... the METAR and ATIS recording are both produced at the same time locally by the local weather observer (u

You have it backwards, ATIS doesn't pull from METARs... the METAR and ATIS recording are both produced at the same time locally by the local weather observer (usually a controller in the tower), reading raw data directly from the on-field weather station and making manual edits as necessary. The two should match up exactly, but that's because they're both produced by the same process. If the tower is closed, or it's an untowered field, the system can run in automatic mode. In that case the radio broadcast gets updated every minute, much more frequently than METARs get updated (every hour).