How did Snape find Harry and Hermione in the Forest of Dean?
While this question answers how Snape knew Harry and Hermione were in the Forest of Dean, how did he know exactly where to send his patronus so that Harry would see it and be led to the sword of Gryffindor? Wikipedia indicates the area is over 110 square kilometers in size, so it would not have been an insignificant task to locate one small tent.
Did Snape over come the protective spells that Hermione would have cast or did he use another method to locate Harry? Or did Hermione forget to cast the protective spells (perhaps because of Harry's state at the time), which would account for Harry and Ron finding their way back in this question?
Purely speculating here, but Ron used the Deluminator to find them, and it seemed to guide him quite precisely to their location. It's possible that Dumbledore had another similar magical item (or another Deluminator) that he'd created, which Snape used to locate them as well.
@apollo Clearly not a duplicate—that’s the question that inspired this one, and as this question mentions, it only answers how Snape knew they were in the Forest of Dean, not how he knew _where_ in the Forest of Dean they were.
@apollo ‘Related’ doesn’t mean ‘duplicate’. They very clearly are related, and the other question appears in the _Linked_ section in the sidebar on the right as it should; but they are not the same question, and their answers differ quite fundamentally. There would have to be some extensive editing to make it one question, and that editing would invalidate several answers already given, which is considered a big no-no.
Surprised you accept Steam’s answer rather than Slytherincess’ – would you care to say why?
@PJTraill Primarily because of this comment. https://scifi.stackexchange.com/questions/17727/how-did-snape-find-harry-and-hermione-in-the-forest-of-dean/17742#comment33020_17742
Depending on how the Patronus charm works, Snape has at least one method of locating Harry. As we have seen in several instances, the Weasley wedding and Harry's return to Hogwarts, the Patronus Charm can be used to deliver messages. In this case, the spirit guardian flies off toward the intended recipient. Considering that Snape has shown the ability to fly, it would not be inconceivable for him to Apparate to the Forest of Dean (to avoid tails) and proceed to cast and follow his Patronus to wherever Harry is.
But do we know that the Patronus can always locate the target, or only when one knows where they are anyway?
If the Patronus located the target, then e.g. Voldemort could only send Patronus to find Harry. Or vice versa, Dumbledore could track down Voldemort long before the Second wizarding war...
@byk7 Voldemort was not able to do the Patronus charm, and Dumbledore wouldn't hunt down Voldemort because it was not up to him to defeat Voldemort according to the prophecy. I believe the question about why Dumbledore didn't just hunt down Voldemort has been answered either on stack or Quora.