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The Rapid Refresh (RR or RAP) is a numerical weather prediction (NWP) model. The model is designed to provide short-range hourly weather forecasts for North America. The Rapid Refresh was officially made operational on May 1, 2012, replacing the Rapid Update Cycle (RUC).
The Rapid Refresh is run at the NOAA National Centers for Environmental Prediction (NCEP). It is based on the framework of the Weather Research and Forecasting model (WRF); the Global Forecast System (GFS) provides the boundary parameters. The grid points are spaced every 13 kilometres (8.1 mi), with 50 vertical intervals extending up to the 10-hectopascal (10 mb) level of the atmosphere. The model runs once each hour, with forecasts given hourly out to 18 hours.
An experimental version of the Rapid Refresh runs at the Earth System Research Laboratory (ESRL), a NOAA unit that develops models in the research stage prior to operational implementation. This version uses more modern model framework and also has a higher-resolution mode, the High Resolution Rapid Refresh (HRRR), that uses a 3 km (1.9 mi) grid spacing and gives forecasts in 15 minute intervals (though still only issued once an hour).