There is a forecast that will give me an estimate of the numbers, but the actual day will still differ, the key is to look out and it's estimated gap is.
There is an estimate that will give me an estimate, but there will still be a discrepancy on the day, the key is to see how much difference between the discrepancy and its estimate.
There is an estimate, I will be given an estimate of the number, but the actual day there will be differences, the key is to see the difference between the difference and its estimate.