My suggestion is to notify the OP when someone votes to close his question informing him the reason behind the vote. The reason is:
Most users don't leave a comment when voting to close, and most OP leave the question alone after asking it waiting to receive an answer.
If an OP came back the next day, say he posted in the evening and checked on his question the next day, there's a high possibility that the question would be voted down and closed by then.
If the OP is notified immediately after the first close vote, they have time to fix the question before it gets down-voted and closed.
It happened to me recently, I received my first close vote, the voter didn't leave a comment, I read the reason, added an single example of what I want and rephrased my question immediately after the vote, and didn't receive any close votes since.
Many questions get close votes for misunderstanding, notifying the OP might save them.