[gembud] GEMPAK GRIB Bug?

I have searched the GEMBUD and GEMPAK support lists and have not found this
reported by anyone else, but it seems that NAWIPS/GEMPAK has an issue with
GRIB records where the decoded values should be an entire grid of zeros (a
s sometimes happens with precipitation and hydrometeor fields in limited ar
ea mesoscale models).  I have found this problem using a Linux build of NAW
IPS/GEMPAK that I have built from source using g77 and gcc.  I have found i
t to be a problem on both 32-bit Linux and 64-bit Linux (RedHat in both cas
es).  Here is a detailed description of what I did and observed:

1.  GRIB edition 1 files (created by the NCEP-developed WRF post-processor
) are decoded with dcgrib2 as follows:  dcgrib2 myfile.gem < myfile.grb
2.  Rendered the total precipitation forecast from the resulting GEMPAK fi
le and find a corrupted, noisy image that changes patterns each time I hit reload. Additionally, the rendering generates the following error in the E
rror status window:
[DG2] Too many maxs found -- increase radius or reduce range

1.  Ran the GEMPAK file through "gdlist" to see min/max values actually co
ntained in the GEMPAK file.  It reports a combination of zeros, 10.0s, 20.0
s, and 30.0s.
2.  Ran the original GRIB file through wgrib and IDV and verified the orig
inal GRIB field is encoded correctly and that all grid points actually are 0.

The attached tar ball has the original GRIB record, the resulting GEMPAK fi
le created from dcgrib2, and the sample NAWIPS image demonstrating the prob

Thanks for your help in advance!  Please let me know if you need anything e
lse from me.

Best regards,


Brent Shaw
Senior Meteorologist and Project Manager
Weather Decision Technologies Inc<http://www.wdtinc.com/>.
3100 Monitor Ave.
Norman, OK 73072
Office:  (405) 579-7675 x246
Mobile: (405) 397-9950

GIF image

Attachment: sample.tgz
Description: sample.tgz

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