Had to check our forecast before I commented, but this is one of the thought processes that I go through during the warm season. Like two days ago I have no qualms about going "showers likely" but once you get to today I ask myself what public perception is going to be. Are they going to step outside and say it's showering, or it's raining. If it's the latter, I make sure I change the wording from showers to rain.
To that end, I almost always go "rain" when PoP is 75% or greater.