[Wrf-users] Is this warning in WPS 3.8.1 important?

[Douglas Lowe]

Dear all,

While running WPS 3.8.1 using ECMWF meteorology I get this warning message:
WARNING: Entry in METGRID.TBL not found for field ST100255. Default options will be used for this field!
WARNING: Entry in METGRID.TBL not found for field SM100255. Default options will be used for this field!

Comparing the METGRID.TBL for 3.8.1 with that for 3.4.1 I find that the entry for ST100255 has been replaced
by an entry for ST100289 (same for SM100255).
<         fill_lev = 289 : ST100289(200100)
---
>         fill_lev = 255 : ST100255(200100)

However my met_grid files have only the ST100255 variable, and no ST100289 variable.
Which is because the Vtable (which I'd copied from my original 3.4.1 setup) has ST100255 not ST100289.

Comparing the default Vtables for 3.4.1 and 3.8.1 I find that ST100289 is essentially ST100255, just with a different variable name. And looking in Registry.EM_COMMON for v3.8.1 I can find an entry for ST100255, but not one for ST100289 - so WRF would not actually be aware of this variable if I were to use it.

So, I guess what I need to do is modify METGRID.TBL to use ST100255 again (instead of ST100289). However, I'd like to also ask 

Why was WPS modified to use the ST100289 variable, but WRF hasn't? Was this in preparation for a change which has now been made in WRF 3.9.1? Should I modify METGRID.TBL to use ST100255 again (instead of ST100289), or would a better solution be to back-port some code from v3.9.1 which uses ST100289 to my version of v3.8.1 (I'm not going to move up to 3.9.1 yet, because we've too many local changes to the code to move versions every year)?

Thanks,
Doug