The Rapid Update Cycle (RUC) was an American atmospheric prediction system that consisted primarily of a numerical forecast model and an analysis system to initialize the model. The first operational implementation was created in 1994, with 60km resolution and a 3-hour cycle. 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 Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...

-sensitive users, such as those in the aviation community. Significant

weather forecasting Weather forecasting or weather prediction is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather info ...

problems that occur in the 0- to 12-hr range include severe weather in all seasons (for example,

tornado A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the ...

es,

thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustics, acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorm ...

snow Snow consists of individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water througho ...

, and

ice storm An ice storm, also known as a glaze event or a silver storm, is a type of winter storm characterized by freezing rain. The National Weather Service, U.S. National Weather Service defines an ice storm as a storm which results in the accumulatio ...

s) and hazards to aviation (for example, clear air turbulence, icing, and

downburst In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. It originate ...

s). The RUC ran at the highest frequency of any forecast model at the

National Centers for Environmental Prediction The United States National Centers for Environmental Prediction (NCEP) delivers national and global weather, water, climate, and space weather guidance, forecasts, warnings, and analyses to government agencies and private users. The centers f ...

(NCEP), assimilating recent observations to provide very high frequency updates of current conditions and short-range forecasts. This update frequency was only once an hour (the standard interval for

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observation reporting), and with computational limitations and the time required to assimilate all of the data, there is approximately a one-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 grid spacing, but also covers a wider area. An experimental High Resolution Rapid Refresh (HRRR) ran by the Earth System Research Laboratories (ESRL) offers resolution at 15-minute intervals.Rapid Refresh information page
NOAA. Retrieved 2010-05-15. A backup version of the RUC continued to run until that too was stopped on May 15, 2013, thus formally bringing an end to the model.

References

External links

NCEP RUC Homepage
– Includes forecast output images and descriptions of the diagnostic variables available from the model output. {{Atmospheric, Oceanographic and Climate Models National Weather Service numerical models