In this case, treat a bank like you would a family member; let them know that you will be out of the country for a period of time and they will make a note of it on your account. Whenever any transactions occur it may cause an automatic tripping of a flag on your account, but a human will be able to read the note. This has helped me greatly in the past.

PS: This can also (and should also) be done on your credit card accounts.