Rapid update cycle

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.

Graphical 12-hour forecast output from RUC2

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 was only once an hour (the standard interval for ASOS 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 13 km (8.1 mi) grid spacing, but also covers a wider area. An experimental High Resolution Rapid Refresh (HRRR) ran by the Earth System Research Laboratory (ESRL) offers 3 km (1.9 mi) resolution at 15-minute intervals^[1] 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

↑ Rapid Refresh information page. NOAA. Retrieved 2010-05-15.

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

Model types

Atmospheric model Climate model Numerical weather prediction Tropical cyclone forecast model Atmospheric dispersion modeling Chemical transport model Upper-atmospheric models Ensemble forecasting Model output statistics Meteorological reanalysis Parametrization

Specific models

Climate	IGCM HadCM3 HadGEM1 GFDL CM2.X CGCM CCSM CFSv2 ECHAM MPAS

Global weather	IFS (ECMWF) FIM GEM GFS NAEFS NAVGEM UM JMA GME ARPEGE

Regional and mesoscale atmospheric	NAM RR / RAP RAMS WRF RAQMS HIRLAM LAPS RPM

Regional and mesoscale oceanographic	HyCOM ROMS POM MOM FVCOM MITgcm FESOM

Atmospheric dispersion	ADMS AERMOD ATSTEP AUSTAL2000 CALPUFF DISPERSION21 ISC3 MEMO MERCURE NAME OSPM PUFF-PLUME RIMPUFF SAFE AIR

Chemical transport	CLaMS MOZART GEOS-Chem

Land surface parametrization	JULES CLASS ISBA

Discontinued	AVN / MRF / GSM Eta LFM MM5 NGM NOGAPS RUC

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