Information about CSU real-time 4-km WRF model forecasts

28 April 2013

• We are running a single WRF-ARW forecast at 4-km horizontal grid spacing. This is a "convection-allowing" forecast, in that deep convection is explicitly predicted by the model, but is not necessarily fully resolved. For the spring and summer of 2013, these forecasts are being run over a domain covering the western and central US in support of the MPEX field campaign. One forecast is being initialized each day at 1200 UTC and run out for 39 hours. As computing resources allow, we will also run a forecast initialized at 0000 UTC and run out for 48 hours. NOTE: Now that the MPEX campaign has ended, there will be one run per day, initialized at 0000 UTC out to 48 hours.
• The full domain is shown in the image below; it comprises 748x600 grid points with 51 vertical levels on a stretched grid with higher resolution near the surface.

• We are using WRF-ARW version 3.4.1 for these 4-km forecasts.
• These runs use a 25-second timestep.
• Currently, the 1200 UTC run finishes around 1:45 pm Mountain Daylight Time, and post-processing is completely finished a bit after 3:00 pm MDT.
• Graphics showing simulated radar reflectivity are calculated by the model to be consistent with a 10-cm radar (such as the "NEXRAD" radars) and with the cloud microphysics scheme being used.
• Graphics showing simulated satellite brightness temperatures were developed in collaboration with Dan Lindsey and Louie Grasso of CIRA.
• The forecasts are running on a 144-core Infiniband cluster at the Department of Atmospheric Science, Colorado State University.
• Other details of the model configuration is given in the table below:

	CSU 4-km forecast
Initial/Boundary conditions	0.5 degree GFS forecast, BCs updated every 3 hours
Boundary layer	MYJ
Microphysics	Morrison two-moment
Land surface	Noah
Shortwave radiation	RRTMG
Longwave radiation	RRTMG

(More info on the WRF physics options can be found on the WRF website here.)