(1) Load compiler and NetCDF using modules Type ". /usrx/local/Modules/default/init/bashâ" (there is a space between the dot and the path and depending on your shell you may need to select a different shell option) Type "module load EnvVars" and "module load ibmpe" and "module load ics" and "module load lsf" and "module load NetCDF" and "module load HDF5" (2) Make sure your build environment has the following variables defined: export WRFIO_NCD_LARGE_FILE_SUPPORT=1 export WRF_DFI_RADAR=1 (3) Go into hrrr_wrf.fd/WRFV3.4.2 (4) Type "./clean -aa" (5) Type "./clean -a" (6) Type "./configure" (7) Enter option "15" and then opti "1" and that will create a configure.wrf file with all the compilation flags (8) Open the configuration file "configure.wrf" and make the following changes before saving and exiting the file: Change From: DM_FC = mpif90 -f90=$(SFC) DM_CC = mpicc -cc=$(SCC) -DMPI2_SUPPORT ... FCNOOPT = -O0 -fno-inline -fno-ip To: DM_FC = mpiifort DM_CC = mpiicc -DMPI2_SUPPORT ... FCNOOPT = -O2 -fno-inline -fno-ip (9) Type "./compile em_real >& compile.log.YYYYMMDDHH" and that will build WRF (will take 10-15 min) (10) The WRF executables will be located in WRFV3.4.2/main/real.exe and WRFV3.4.2/main/wrf.exe (11) Rename the old executables in the exec directory by typing "mv /nwprod/hrrr.v1.0.0/exec/hrrr_real /nwprod/hrrr.v1.0.0/exec/hrrr_real.YYYYMMDDHH" and "mv /nwprod/hrrr.v1.0.0/exec/hrrr_wrfarw /nwprod/hrrr.v1.0.0/exec/hrrr_wrfarw.YYYYMMDDHH" (12) Copy and rename the new executables into the exec directory by typing "cp main/real.exe /nwprod/hrrr.v1.0.0/exec/hrrr_real" and "cp main/wrf.exe /nwprod/hrrr.v1.0.0/exec/hrrr_wrfarw"