The Rapid Update Cycle (RUC)

Precip/MSLP/1000-500 thick - 12h fcst

Aviation Flight Rules - 12h fcst

Tropopause Pressure - 12h fcst

was

NOAA

NCEP

A numerical forecast model (using isentropic-sigma hybrid vertical coordinate) and
An analysis/assimilation system to initialize that model.

Developed to serve users needing frequently updated short-range weather forecasts, including those in the US aviation community and US severe weather forecasting community.
The Rapid Refresh (RAP) is the next-generation version of the 1-h cycle system, and replaced the operational RUC at NCEP at 12z on 1 May 2012.
8 May 2012 - An experimental version of the RUC continues to run at ESRL for an undetermined period of time but likely through much of 2012.

News items

1 May 2012 RAP operational implementation at NCEP occurred at 12z on 1 May 2012 as planned. The last NCEP RUC run was 11z today.
19 Mar 2012 30-day Rapid Refresh evaluation completed with recommendations for implementation but due to other computer complications, the NCEP RAP implementation is now no earlier than 3 April 2012. More news will be posted as it becomes available.
14 Feb 2011 Rapid Refresh testing continuing at NCEP/EMC as well as at ESRL, NCEP implementation now planned for Oct-Nov (updated 7/22) 2011. The RAP is showing improvement over RUC forecasts for wind, RH, temperature, and heights at almost all levels and forecast durations. ftp access for RR grids is now offered by NCEP -- see this recent RUC forum post from Geoff Manikin at NCEP.
16 Sept 2010 Progress continuing with Rapid Refresh testing at ESRL (see http://rapidrefresh.noaa.gov ), real-time testing at NCEP underway.
2 March 2010 - RUC upgrade (although not completely installed until 20 April 2010. Explanation ): Extension of RUC to 18h every hour, modification to hybrid coordinate, addition of Canadian aircraft observations. More info available at http://www.nws.noaa.gov/om/notification/tin10-07aaa_ruc_changes.txt
4 Dec 2009 Problem with radar reflectivity ingest into NCEP-operational RUC starting early August, script updated to changed directory Tues 1 Dec.
12 Nov 2009 Rapid Refresh/RUC review presentation - latest news - PDF
14 Oct 2009 TAMDAR moisture observations restored to RUC (and NAM) for NCEP runs today after 50-day absence due to upstream metadata change. TAMDAR moisture observations have been available all along for all ESRL/GSD RUC runs.
31 Mar 2009. NCEP implementation at 12z with improved snow cover and improved cloud analysis, see Info PDF here. - February RUC forum post on this topic
16 Dec 2008. TAMDAR data added to operational RUC at NCEP
17 Nov 2008. RUC upgrade implementation at NCEP Assimilation of radar reflectivity added, longwave radiation changed to RRTM scheme, convection (Grell-Devenyi) changes. Extended RUC upgrade ppt here for pre-implementation briefing
8 Jan 2008. RUC crisis change for improved cloud/vis assimilation, wind gust, precip type. Post on RUC forum , PDF
11 Dec 2007. RUC/RR summary Powerpoint/pdf presented at NCEP Production Suite Review meeting.
4 Dec 2007. 13km/hourly RUC grids became available via NOAAPort and Family of Services. See RUC Forum post
Reflectivity real-time products available for devRUC13 and backup RUC13 uns since April 2007.
4 April 07 - 3-d radar reflectivity data assimilated hourly in experimental devRUC13 since Feb07 and now in backup RUC13 as now. An example of the effect of radar reflectivity assimilation in available here
28 June 2005 -- 13km RUC operational implementation at NCEP --
-- Higher resolution, additional observation types assimilated (GPS PW, METAR cloud/vis, RASS, improved use of GOES cloud-top), improved moisture analysis, improved cloud/precip physics.
- RUC13 pre-implementation briefing
RUC journal articles available in Feb 2004 Monthly Weather Review.
Mesoscale Weather Prediction with the RUC Hybrid Isentropic Terrain-Following Coordinate Model. pages 473-494. [GSD PDF version]
An Hourly Assimilation-Forecast Cycle: The RUC. pages 495-518. [GSD PDF version]

The key features of the RUC include:

high-frequency (every 1h) short-range weather model forecasts (out to 12+ h) in support of aviation and other mesoscale weather forecast users
high-frequency (every 1h) 3-d objective analyses over much of North America, including the contiguous United States and adjacent areas of Canada and Mexico, assimilating the following types of observations:
a hybrid isentropic-sigma vertical coordinate.

Other RUC Information, Real-Time and Archived Data

Real-time RUC gridded data available from

Archived RUC gridded data available from:

Information on gridded data

RUC grid files - Information on contents
RUC13 GRIB table-updated 17 Nov 2008 with RUC upgrade
(see RUC20 table for GRIB document links)
Previous RUC13 GRIB table as of Sept 2005
RUC20 GRIB table with GRIB document links
RUC analysis obs and background error specifications

Model fixed fields - topography, etc.

Download RUC fixed fields (ASCII) and software
- 13km topography, mini-topography, lat/lon, land-use, roughness length, soil type
- 5km RTMA topography (used for RUC-RTMA downscaling)
- 20-km, 40-km and 60-km topography or latitude/longitude
- 20km land-use, look-up table for roughness length, albedo, emissivity
- software to convert from RUC native coordinates/variables to isobaric coordinates/variables
13-km RUC terrain elevation map
20-km RUC (pre June05) topography map
NCEP daily sea-surface temperature file currently used in RUC
Lightning coverage - Env Canada