ShotOne, thanks for that.
I have witnessed this phraseology being used by aerodrome controllers in many locations - normally in situations such as low vis ops or helis operating from "uncontrolled" surfaces. Perhaps it's crept in from FISO speak or maybe as a reminder to the pilots that "I'm not visual with you and/or some or all of your intended operating surface" or "I can't guarantee that surface is 100% safe for use".
I would like to see the document/publication that approves the use of that phrase in a controlled environment. I have not found it in CAP413.