Forewarning: Redundancy ahead

I heard the word "forewarned" used this week, and I've been mulling it over since. If ever our dictionaries offered a superfluous word, forewarn is it.

According to official sources, forewarn is defined as "To warn in advance."

In advance---isn't the very nature of a "warning" that it be delivered in advance? If you encounter someone under a pile of lumber and say, “Watch out when you stand under that porch, it's really shaky”, you haven't warned them, you've simply reported to them the now-obvious facts. In fact, the definition of warn is "To make aware in advance of actual or potential harm", so forewarn manages to be a single-word redundancy.

Next time you want to forewarn someone of imminent danger, please provide even more help by eliminating the time required for the extra syllable and simply warn them of what's coming.They'll appreciate it. And I will, too.