Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum

RUC failures today

Posted By: Geoff Manikin
Date: 21-January-10 1814Z

The operational RUC (as well as the backup) have been failing since the 03z cycle today, 21 January. We are not completely certain, but it appears that the source of the problem is CFL instability associated with the incredibly strong jet core (over 100 m/s) moving into the domain through the western boundary. The model time step has been reduced from 20 to 15 seconds, and tests have shown this to fix the problem. NCEP Central Operations successfully reran the 16z cycle with this change, and it is now in the model in real-time beginning with the 17z cycle. I'm not sure when it was changed in the backup, but I believe that it was around the same time. The impact on the run time is still being assessed, but it appears that forecast hour 12 products may be delayed by approximately 4 or 5 minutes. We may apply more computer resources to the operational RUC jobs to gain back the lost minutes, but that will be assessed after we are confident that the model is again running without failures. We apologize for today's problems.

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