But one must also realize that Lee's army was in the same condition, having marched an even more roundabout route and fought the same battles for 3 days mostly on the offensive. So they would have been just as tired and disorganized in their structure because of losses. 24 to 48 hours is not a large lead when the army you are pursuing is carring their wounded, their baggage and artillery trains before them.
Had Lee remained on the battlefield, Meade would have surely attacked him. But once Lee withdrew it was a different matter as to why Meade was not more aggressive in the usage of his cavalry, or his sluggish pursuit of Lee in general. In my evaluation as poor as it may be, If Meade was not derelect in his duty in his pursuit of Lee's then there had to be other military reasoning other than weather or some other factor that would have effected both armys.
One of those factors may well have been the passes which Meade mentioned in this report. Those natural funnels would have been excellant defensive positions which would have been difficult to break in the assualt. That may have been one of Meade's concideration. Fighting there would have given Lee a great advantage. Lee used these mountains as shields in getting to Gettysburg and when he withdrew. He did that for good tactical military reasons. It gave him an advantge he wanted.