From what I understand of this graphical depiction, a big rain storm with a name is going to literally be over Korea. Quite possibly during this weekend. Thought you should know.
EDIT: Alas the monsoon/typhoon/tropical storm has gone off towards China instead now. Rumors that it was pulling a Trollface are unconfirmed. Rain of some amount is still forecast for tomorrow, but it might be all done before the race even starts. Given Qualifying results I hope it's still wet when the race starts.
Here's another forecast graphic: