An animated 3-D plot of RAP forecast data valid from 0000 UTC through 1800 UTC on July 11, 2012. This forecast loop shows simulated composite radar reflectivity on the surface and a 25 m/s isosurface of wind speeds aloft. Stretching from Hudson's Bay to the Atlantic is a vertical profile of relative humidity, red showing high relative humidity and blue showing drier air. This image was generated with Unidata's Integrated Data Viewer (IDV).
The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental Prediction (NCEP), RAP runs with two versions. The first generates weather data on a 13-km (8-mile) resolution horizontal grid and the second, the High-Resolution Rapid Refresh (HRRR), generates data down to a 3-km (2-mile) resolution grid for smaller regions of interest. RAP forecasts are generated every hour with forecast lengths going out 18 hours. Multiple data sources go into the generation of RAP forecasts: commercial aircraft weather data, balloon data, radar data, surface observations, and satellite data. More information on the RAP and HRRR are available at the RAP home page. Data are available for download through the National Model Archive and Distribution System (NOMADS).
A plot of RAP forecast surface visibilities valid at 0700 UTC on July 11, 2012. This image was produced with the Grid Analysis and Display System (GrADS).