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Rapid Update Cycle (RUC)

An animated image of RUC accumulated precipitation forecast from August 14, 2011 at 09UTC to 18UTC. During this period, heavy rains fell over northern New Jersey and New York City. This image was produced with the Grid Analysis and Display System (GrADS) and ImageMagick.

The Rapid Update Cycle (RUC) weather forecast model was developed by the National Centers for Environmental Prediction (NCEP). On May 1, 2012, the RUC was replaced by NCEP’s Rapid Refresh (RAP) weather forecast model. The RUC was designed to produce quick, short-term, weather forecasts using the most currently available observations. When it was first implemented in 1994, the model was run every three hours making forecasts out to 12 hours. By 2002, the RUC was run every hour, on the hour, producing 12-hour forecasts. The RUC domain covers the continental United States at two different resolutions, depending on the date on which the weather forecast was generated. More information on the RUC is available at the RUC homepage. Gridded RUC data are available from NOMADS and the RUC homepage.

A plot of upper-air temperature and relative humidity over New York City valid at 18UTC on August 14, 2011, from a RUC 12-hour forecast. High relative humidity at 700hPa (approximately 10,000 feet) and 500hPa (approximately 18,000 feet) indicate cloud layers. This image was produced with the Grid Analysis and Display System (GrADS).