The data for the tutorial case is valid at 12 UTC 5 February 2008. The first guess comes from the NCEP FNL (Final) Operational Global Analysis data, passed through the WRF-WPS and real.exe programs.
To run WRF 3D-Var, first create and enter into a working directory (for example, $WRFDA_DIR/workdir), and set the environment variable WORK_DIR to this directory (e.g., setenv WORK_DIR $WRFDA_DIR/workdir). Then follow the steps below: