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Some bug fix changes are upcoming to the NCEP RUC, both in the post-processing and model forecast programs.
First are the post-processing changes, now scheduled for implementation on Tues 24 Sept (and subject to change based on critical weather day designations, etc.). 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 http://ruc.fsl.noaa.gov/forum/eval20/?read=1053).
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).
Second are the model changes, scheduled at this time for implementation on Tues 8 Oct. There are two set of changes here, one to ensure accurate 2m temp forecasts over thin snow cover. This is a RUC land-surface model change. It avoids too-cold forecasts over thin snow cover at night. Since the RUC20 with the new 2-layer snow model and frozen soil processes was not implemented until 17 April after most of the 'snow season'was over, most users have never seen this problem, and thanks to this change, never will. The other change to the RUC model is to correct a bug that was resulting in too much shortwave radiative heating in the atmosphere. There was no bug in the SW radiation reaching the surface, so the effects of this fix are relatively small, but will result in a slight cooling effect (less than 0.5 deg C) primarily in daytime.
Stan Benjamin
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