WRF-NMM Users Page

WRF Modeling System Updates

The WRF model tar file has been updated to Version on August 22, 2008.

WRF Version new features, updates and bug fixes

WRF-NMM specific updates

  • Single-domain restarts. The restart files from NMM had not been identical for equivalent points in time based on an original forecast start time. That has been fixed by increasing the number of restart variables, avoiding the zeroing of some accumulations, and by computing the solar distance repeatedly during the forecast. NMM nest restarts are not working properly and should not be attempted at this time.
  • Noise originating on the eastern boundaries of NMM nests when mountains are present there has been significantly reduced.

General updates


  • Use of Kain-Fritsch convection (cu_physics=1) in the NMM has been repaired by properly computing values of W(=dz/dt) on model layer interfaces for input to that scheme.


  • Overdecomposition. Version 3.0.1 was released with code that detects when a WRF domain would be decomposed by too many processors, resulting in per-task subdomains that are too narrow in one or both horizontal dimensions. The code either generates an error and aborts (default) or attempts to correct by reducing the number of processors (compile time option, to enable see comment in configure.wrf file). This new feature as released in 3.0.1 was too sensitive, however, triggering error and aborts or processor reductions on domains that were within safe decomposition limits. This fix corrects that problem.
  • Default compiler optimizations on IBM. Version 3.0 and 3.0.1 were released with "-O3 -qhot" as the default optimization settings. However, a number of problems with accuracy and execution stability have been reported with the -qhot setting, so this option has been commented out in this update, leaving just -O3 as the default setting. The -qhot option can be reenabled by removing the '#' comment character on the FCOPTIM line and recompiling. The option does improve computational performance and the issues with -qhot appear to depend on WRF configuration and xlf compiler version, but until we have a better understanding (or until the issues are resolved) use of -qhot is at the user's discretion and risk.
  • A missing comment character needed to be added to the Grib edition 2 portion of the IO for the code to compile, which is an optional portion of the WRF system to build.