I just got back in town, and I've been going thru the ARWpost.exe discussion. What I'm seeing looks quite familiar, as I can make WRF 3.7.1 do the same thing when "afwa_diag_opt" is 1.
I've been working quite a while with WRFHELP on this one, though I ultimately found the cause. WRF (and presumably ARWpost) has a lot of different array variables that it uses. It isn't practical to allocate memory for every array in existence, as not all arrays are used. WRF handles this via files in the Registry directory. These file are basically descriptions of various options and their dependencies. This includes array dependencies/ Arrays that are needed get allocated. If a required array isn't listed, it isn't allocated. Eventually, when WRF tries to use the unallocated variable, you get a memory corruption along with the same ugly traceback that others have seen.
I've seen it mentioned that only certain variables trip the crash. This supports the same behavior with WRF.
The bottom line is that this is a bug with the code for ARWpost.exe.
Kevin W. Thomas
Center for Analysis and Prediction of Storms
University of Oklahoma