X and Y axis Plots with cross section

[Alan Klein]

I am trying to produce a simple cross-section containing RH, T, and SFC P. I have no problem with
plotting the RH and T (from 1000mb-150mb). However when I plot SFC P, a second y axis and y
axis are plotted (same values as the RH/T set, but shifted as if the scale is somehow different). I
have set all of the data to the same range, but am not sure why the surface pressure plot is
shifted.
My code for the basic set-up is:
'set lon 250 273'
'set lat 45'
'set lev 1000 150'

And to set the surface pressure to plot on the same scale, I have tried both of the following with
the same undesired results:
'set axlim 1000 150'
'set vrange 1000 150'

Any idea as to what I need to fix to plot this correctly?

If someone has a better way to show where the surface is, perhaps that is better.

Thanks for the help in advance,
--Alan Klein