compare 2 column cells and return the adjacent columns cells data of the cell
 

In cell (P4) there is a formula that gives a number in C-mils (example "89268") based on several manualy inputer numbers.
I have a chart that has (AT4) through (AT33) each row of this column has a higher C-mill number example (AT14) = 83690 and (AT15) = 105600. in the column to the right of (AU) is a I want to reference back to (Q4).

such as the number in P4 is =(AT14) and <(AT15) and I want the number in (AU15) "1/0" is returned to (Q4).

remember the number in (P1) could be any number between "1 and 2,000,000" and this range is not divided equaly between cells (AT4) and (AT33). The number to the right in Column (AU) must be the cell that is the greater of the 2 cell number of the 2 adjacent cells in Column (AT) =(AT14) <(AT15).

I have used this formula to find the information in the columns "=VLOOKUP(P8,$AT:$AU,2,0)" however this will not take into account that (P8) may never match the information in column (AT) of the table, what I need is the next higher value in the column, lets say, in column (AT) cell (AT7) is less than (P8) and cell (AT8) is greater than (P8) what I would like is... if (P8) = (AT7) get (AU7) and if (P8) is (AT7) but < or = to (AT8) then get (AU8)

this is the table I am pulling data from, if I input 30128 in cell (P8) I want the cells in (AT) referenced to find the correct information in (AU) in this case the answer I am looking for is (AU) "4"

(AT) (AU)
C-mils GAUGE
1620 18
2580 16
4110 14
6530 12
10380 10
16510 8
26240 6
41740 4 <====<
52620 3
66360 2
83690 1
105600 1/0
133100 2/0
167800 3/0
211600 4/0
250000 250kcm
300000 300kcm
350000 350kcm
400000 400kcm
500000 500kcm
600000 600kcm
700000 700kcm
750000 750kcm
800000 800kcm
900000 900kcm
1000000 1000kcm
1250000 1250kcm
1500000 1500kcm
1750000 1750kcm
2000000 2000kcm