Quick Tip: Required field TT not found with ungrib on WRF 3.x

Dec 9, 2019

If you are running WRF 3.x series with the NCEP GFS data updated some time in 2019 you may have found an error along the lines of:

ERROR: The mandatory field TT was not found in any input data.

There may also be an error with metgrid.exe where you get:

ERROR: Error in ext_pkg_write_field

How to fix?

This is because the GFS data was updated in June 2019 with a new format (solution credit of this link, retrieved 12/9/2019).

The solution is rather simple: compile the version 4.0 of the WRF PreProcessing System (WPS) and use ungrib.exe from there. You don’t need to change the Vtable or anything else in your existing 3.x WRF+WPS installation.

This is a quick tip post. They are written in a way to help users quickly resolve a problem that I ran into in my daily work and usually don’t go in depth about the details of ‘why’. Please feel free to comment or contribute to the knowledge.