Rapid Refresh (RAP) is the next-generation hourly-updated replacement for the Rapid Update Cycle (RUC) numerical model covering North America. The National Centers for Environmental Prediction (NCEP), along with the Earth Systems Research Laboratory (ESRL) have been running the RAP model experimentally for some time, and NCEP plans to switch to the RAP for operational use on Tuesday, May 1 2012. (If May 1st is a Critical Weather Day, the transition will take place as soon as practical afterward).
For more information on the RAP model and on the transition plan, see these resources:
- The Rapid Refresh info page at http://rapidrefresh.noaa.gov/.
- Detailed information on the changes from the RUC model to the RAP model are available in this Technical Implementation Notice from the National Weather Service.
- Detailed information on products generated with the RUC model that will not be available from the RAP model is available in this Public Information Statement.
- Examples comparing output from the RUC and RAP models are available from http://www.emc.ncep.noaa.gov/mmb/gmanikin/rap/para/.
Rebecca Cosgrove of NWS/NCEP Central Operations in Camp Spring, MD is an NCEP representative to Unidata's Users Committee. She is heavily involved in implementing the RAP model at NCEP, and has generously offered to field questions about the transition from RUC to RAP.
RUC2 grids will be replaced by RAP grids in the IDD CONDUIT and NGRID datastreams at the time that NCEP implements the change. Unidata has been assured that the goal of the RUC2 to RAP transition is to have little to no impact on end-users. This will be accomplished, in part, by keeping the model ID and area coverage the same in replacement RAP products as they are in current RUC2 products. We believe that the transition will be completely transparent for NOAAPort SBN-delivered/IDD-relayed NGRID products. However, the impact of the transition on CONDUIT grids may or may not require end-user modifications to LDM pattern-action file entries.
For additional information on the implications of the transition for CONDUIT users, please read this message from the CONDUIT mailing list.