The INTERPF program sets the initial and boundary conditions for the meteorology simulation. The analysis from RAWINS is interpolated from its native vertical coordinate (pressure) to the forecast model's vertical coordinate (a terrain-following “sigma” coordinate). In addition, the state variables are converted as necessary, e.g., relative humidity to specific humidity. Also, INTERPF interpolates the analysis fields for the MM5 staggered grid configuration (discussed in Section 3.6.2) and interpolates the lateral boundary conditions to the sigma coordinate and staggered grid.