What’s interesting about your chart is that as Obama’s approval looks better, so does his national polling. The question is why do voters feel better about him in the last 2 weeks? Some of it is Sandy but not all.
Historically, there is almost always a rallying to the incumbent in the week or so before the election as he locks down some of his wavering supporters. As the week winds down, however, that number usually changes very little and the remaining undecideds break heavily for the challenger.
If form holds, then Obama winds up with right around 48%, which leaves Romney just about 51%. Exactly what Rove is predicting FWIW.