The rapid update cycle (RUC) was an atmospheric prediction system that consisted primarily of a numerical forecast model and an analysis system to initialize the model.
The RUC was designed to provide accurate short-range (0- to 12-hr, later expanded to 18-hr in 2010) numerical forecast guidance for weather-sensitive users, such as those in the aviation community. Significant weather forecasting problems that occur in the 0- to 12-hr range include severe weather in all seasons (for example, tornadoes, thunderstorms, snow, and ice storms) and hazards to aviation (for example, clear air turbulence, icing, and downbursts).
The RUC ran at the highest frequency of any forecast model at the National Centers for Environmental Prediction (NCEP), assimilating recent observations to provide very high frequency updates of current conditions and short-range forecasts. This update frequency is still only once an hour (the standard interval for ASOS observation reporting), and with current computational limitations and the time required to assimilate all of the data, there is approximately an hour delay in producing the forecasts. Because of this, it was common practice to use a one-hour forecast from the RUC as a current analysis, as the one-hour forecast would come out only a few minutes before the time it is forecasting for. There is also little possibility for error in a one-hour forecast, meaning that the RUC's one-hour forecast would not usually vary greatly from the actual state of the atmosphere at that particular point in time.
The RUC was decommissioned on May 1, 2012; it was replaced by the Rapid Refresh (RR or RAP) model, based on the WRF. Like the RUC, the Rapid Refresh model also runs hourly out to 18 hours on a 13-km grid spacing, but also covers a wider area and includes an experimental high-resolution mode that offers 3-km resolution at 15-minute intervals A backup version of the RUC continues to run.
Famous quotes containing the words rapid and/or cycle:
“In clear weather the laziest may look across the Bay as far as Plymouth at a glance, or over the Atlantic as far as human vision reaches, merely raising his eyelids; or if he is too lazy to look after all, he can hardly help hearing the ceaseless dash and roar of the breakers. The restless ocean may at any moment cast up a whale or a wrecked vessel at your feet. All the reporters in the world, the most rapid stenographers, could not report the news it brings.”
—Henry David Thoreau (1817–1862)
“The Buddha, the Godhead, resides quite as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain or in the petals of a flower.”
—Robert M. Pirsig (b. 1928)