"empirical" units ??
I believe the correct term is "imperial" units.
RE: Nice job!
If you just want part of the report, then just find the part of the pretty_print_metar() function you need, and use that. All the data that are pretty-printed are available to you as individual variables, eg $temp_c, $wind_dir_eng etc.
Nice job interpreting metars to display weather. Are you thinking about adding functions to display individual readings so a developer can pick and choose which readings he or she wants to display. I am using your routines on my web page to display readings for three airports near my home.
An open, cross-platform journaling program.
A scientific plotting package.