Change Log for Operational RUC13/20 at NCEP

(20km RUC at bottom)

Change log for operational RUC20 - Apr 2002 - May 2005
Change log for RUC20 in testing before Apr 2002 implementation
Change log for operational 40km RUC - Apr 1998 - Apr 2002

17 Nov 2010 - 1500 UTC

setdpsig.f - Max value of sigma pressure thickness changed from 10 hPa back to 15 hPa.

2 March 2010 (completed 20 April 2010)

Update package to RUC, extension to 18h, addition of Canadian aircraft data, improvement to snow cover. More details at

2 December 2009

Correction to restore access to radar reflectivity in RUC. Had been missing since 4 August 2009.

31 March 2009 - RUC snow cover/cloud fixes

Correction to restore access to radar reflectivity in RUC. Had been missing since 4 August 2009.

17 Nov 2008, completed in Dec - radar reflectivity assimilation, TAMDAR added

More info available under

11 Nov 2008 - correction to RUC land-surface fields

More info available under

13km RUC implementation at NCEP

Tuesday 28 June 2005 - 1200 UTC - NCEP operational implementation

20 Jul 2005 - 1500 UTC

BUFR station list for RUC output BUFR soundings has not been updated on 28 June to new NAM list, but this has now been updated.

26 Jul 2005

Corrected RUC13 code to updated version in /nwprod/sorc on NCEP computer. This does NOT change the RUC execs (or performance) but avoided a drastic problem in the future.

11 Aug 2005

GEMPAK files for SPC, AWC, and HPC were updated to 20km output files instead of previous 40km files.

18 Oct 2005 - 1500 UTC

    Three changes today. See more information here from RUC forum post
  • More detailed 13km topography replacing more smooth field.
  • (hybpost) - Post-processing changes, especially adding surface pressure corresponding to 2m temp level. This fix makes a very big difference for soundings and potential temps from the RUC from AWIPS.
  • (hybpost) - Surface-based CAPE/CIN now included in RUC surface files.

1 Nov 2005

HYBFRONT - hybanl_qc.f
Emergency change so that if all height and wind obs are missing, the resulting height/wind analysis is not changed. (RUC code fix previously made in RUC20 had been missed for RUC13 code.) (Backup RUC from GSD was used, and had no problems in this regard.)

14 Nov 2005

Another emergency fix to avoid problem with duplicate rawinsondes from the same site.

22 Nov 2005

- topo file
Previous smoother topography reintroduced since it was related to crashes that occurred on 12 Nov and 15 Nov. GSD was able to avoid the crashes with a new diabatic DFI, but this will be saved for a later change package.

24 Jan 2006

- RUC grib table
Correct GRIB designator added for 0-1km helicity. Now, 0-1km and 0-3km helicity can be distinguished.

22 Feb 2006 - 1500 UTC

hybhqc.f - Aircraft mean temp bias detection code added to eliminate aircraft with > 3K bias for all reports within a given RUC 1h window. See more information from RUC forum post.

11 July 2006 - 1400 UTC

- Major RUC upgrade package
A significant set of changes on the RUC analysis, forecast model, and post-processing are scheduled for next Tuesday 11 July at 12z. This is the most important set of changes to the RUC since the 13-km RUC implementation in June 2005.
The key differences are:
  • Improved precipitation over oceans and coastal areas.
  • Improved RH forecasts
  • Improved upper-level winds related to improved precipitation
  • Improved surface fields in coastal areas

More detailed information is available at:

5 Sept 2006 - 1200 UTC

inithybv_pre.f - A small package of changes related to lake temperatures was implemented into the operational RUC at 12Z today, 5 September 2006. This is in response to issues with the operational SST analysis providing some very questionable values for certain bodies of water. Similar changes were made to the operational NAM in late August to deal with the same issue.
Climatologies are now used for the Great Salt Lake, the Salton Sea, and Lake Champlain. For several large lakes in northern Minnesota, Manitoba, and Ontario (including Lake of the Woods, Lake Winnipeg, Lake Winnipegosis, and Lake Nipigon), a more reliable lake temperature is used at points where the recent values do not appear reasonable. The value will generally come from northern Lake Superior for deep lakes and northern Lake Winnipeg for shallow lakes.

30 April 2007 - 1200 UTC

hybhqc.f - The mean Obs-minus-bkg (O-B) temperature check for each platform (e.g., aircraft tail number) was modified to trigger for only 8 observations within a 1-h window instead of the previous 20-report threshold. This modification fixes a problem with aircraft with large temperature biases regularly reporting less than 20 reports per hour (resulting in height analysis anomalies on 16 April 2007).

Change log - 20km operational RUC at NCEP - Apr 2002 - May 2005

17 April 2002 - 1200 UTC

Operational implementation of 20km RUC. 40km RUC-2 stops running at this point.

24 September 2002 - 1200 UTC

These changes are primarily for BUFR output, including rotating winds to earth-relative (10m, profiler, storm-relative), setting 1h precip properly (instead of 3h precip on every 3rd hour), and using 2m temps, pressure, and elevation from the RUC 'topomini' file (see The ceiling (cloud base) calculation now properly uses the snow mixing ratio, as well as those of cloud water ice. Also, the precipitation type now properly includes sub-grid-scale precipitation (it did not before).

1 October 2002 - 1200 UTC

Land-surface model fixes for thin snow cover. Fix to shortwave radiation cooling/heating in atmosphere.
Fix so that precip type arrays output on 40km grid are not smoothed, thus avoiding substantial loss to areal coverage.

9 January 2003 - 2000 UTC

A fix was made today (by Geoff Manikin and NCEP/NCO) to correct the date stamp in the RUC BUFR files. The stamp had been running 1 day ahead since January 1. The problem was in a data statement for January, and since the new format for these files began last April, it wasn't until our first January with the RUC20 that the problem surfaced.

27 May 2003 - 1200 UTC

HYBFRONT - 3-d variational analysis
A 3-d variational (3DVAR) analysis was implemented replacing the previous optimal interpolation (OI) analysis. Details in and in a TPB at

Added 0-1km helicity and fixed some other products in post processing -- described in

8 July 2003 - 1900 UTC

Script producing RUC BUFR files
A fix was made today (by Geoff Manikin and NCEP/NCO) to correct a bug in this script which had resulted in the use of the early 'A' RUC analysis run at 0000 and 1200 UTC before most of the rawinsonde is available. Now the BUFR data uses the correct RUC 'B" analysis including the rawinsonde data. The 'B" analysis is the initial condition for RUC model runs at 0000/1200.

BUFR station list
A few stations were added to the BUFR station list, also added at the same time to the Eta BUFR station list.

24 Sept 2003 - 1500 UTC

HYBFRONT - gtresids_sfc_tquv.f, hybhqc.f
A couple of modifications to the 3DVAR initialization were implemented at 15Z today (24 Sep):

  1. Data from land observational sites located at model water grid points will now be flagged. An example of problems associated with this data being assimilated by the model is shown at In this example, data is available at Houghton, Michigan (located on the Keweenaw Peninsula, extending from the Upper Peninsula into Lake Superior). This peninsula is not resolved by the RUC, so the first guess for that location is colder and drier (consistent with a water point in that region) than the observation. A positive increment (difference between observation and first guess) is therefore created by the analysis code and is spread inland, causing unreasonably high temperature and especially dew point values inland over the U.P. It was determined that data from approximately 30 such land stations located at model water grid points will need to be flagged.
  2. The second change is to tighten the thresholds in the quality control checks. Some bad data, particularly moisture observations, has been getting into the analysis, and limiting the permissible difference between the observed value and first guess will reduce the frequency of occurrence.

6 Oct 2003 - 1300 UTC

HYBPOST - hb2mw.f
Fix max wind level diagnostic to prevent intermittent spurious wind max values. The spline interpolation used sometimes can give wild extrapolation from RUC native levels that are very close together. This code fix constrains the spline value to be within 3% of the native level wind max, and adds some other constraints.

11 Oct 2003 - 0000 UTC

HYBETABC (HYBEXT) - (grdtr3d.f)
Fix interpolation routine for interpolating Eta grids to RUC vertical/horizontal grid for boundary conditions. Under a certain rare condition, a divide by zero could occur, so this possibility was eliminated by adding a line of code. A crash that occurred in the 12z 10 Oct run was fixed by this change.

9 Dec 2003 - 1400 UTC

HYBFRONT - (rd_cld.f,hybctp.f)
A change was made to the operational RUC at NCEP today to fix a cloud assimilation error. Cloud was inadvertently being cleared in situations with partial cloud cover in the GOES data in the proximity of a grid point. The overall impact is fairly minor.

14 April 2004 - 1200 UTC

Major change package, including changes to HYBCST , HYBPOST, HYBCST_PRE, and HYBFRONT.
Changes in package described

26 April 2004 - 1600 UTC

RUC analysis changes made on 14 April as part of change package were pulled today due to intermittent moisture/CAPE noise in analysis fields.

28 September 2004 - 1200 UTC

Revised version of RUC analysis implemented, including a revised and more robust version of PBL-based assimilation of surface observations. Also includes constraints for moisture and temperature increments (correction to background) and innovations (obs-minus-background) to improve coherence in analysis fields. More information available here

19 Jan 2005 - 1800 UTC

Fix to treatment of Eta/NAM data in RUC boundary condition code to avoid problem with non-physical lapse rate near surface. See RUC forum for more.

3 Feb 2005 - 1900 UTC

At this time, recovered RUC analysis version with 28 Sept 04 changes. Due to an inadvertent problem with the switch of NCEP Central Operations to a new computer on 25 Jan 05, an older version had been implemented. Today, the 28 Sept 04 version was reinstated. condition code to avoid problem with non-physical

17 Feb, ~18 Mar 2005

Soil moisture updates. Background 1h forecast copied from FSL to NCEP to update soil moisture, which has become too dry at NCEP. The FSL RUC runs includes a soil temp/moisture nudging procedure, to be included in the RUC13, which greatly reduces this problem.

8 March 2005 - 1700 UTC

GETBUFR - getbufr.f - Fix to observation handling problem in case with raob with wind but not mass data data. In this case, winds were being assigned to incorrect station. This was a rare event -- see RUC forum.

18 March 2005 - 1500 UTC

HYBFRONT - hybanl_qc.f - Fix to avoid multivariate height solution when no wind or height available.

Please credit the NOAA/Earth System Research Laboratory, RUC development group, if you wish to use any pictures from this web site.

This page prepared by Stan Benjamin