Note:  While we are transitioning our web pages, products marked with an (*) link to product pages on the old system. Products on those pages are up-to-date, but links on those pages may go to old information or may be broken. Thank you for your patience!

Degrib FAQ

Questions Answered on Other Pages


Answered on Degrib Home/About:
Q. What is GRIB2?
Q. Why create a GRIB2 decoder program?

Answered on Tutorial:
Q. How do I get data?
Q. What if I can't find a sector that I like?
Q. What can I do with the data?

Answered on degrib_dataloc:
Q. Where can I get the NDGD (National Digital Guidance Database)?
Q. Where can I get the NDFD (National Digital Forecast Database)?
Q. What are NDFD sectors?


Questions Answered Here


Q. What are the possible values for "center" and "subcenter"?
A. The center refers to who generated it, and is a look up value in (pdf), while the subcenter is allocated by the originating Center. In GRIB2 they can have a value between 0 and 65535, where 65535 indicates missing.

Q. Why does "tar" keeps producing a "checksum error"?
A. On the Sun platform, the "tar" executable (located under /usr/bin) is not 100% compatible with "GNU tar". Sun users are recommended to look for "/usr/local/bin/gtar".


Degrib: NDFD Frequently Asked Questions (FAQ)

Questions Answered on Other Pages


Answered on
Q. What is the NDFD?
Q. Why Create an NDFD?
Q. How is the NDFD created?
Q. What's in the NDFD?
Q. What are the Benefits of an NDFD?
Q. How accurate are NDFD Products?

  Answered on
(I felt that I could improve on the answers to the questions in bold.)

Questions Answered Here

Q. When will forecast data from the NDFD become available on the Internet as an XML data feed?
Q. What can I do if none of the 16 predefined NDFD sectors matches the area for which I need forecasts?
A. See my instructions on Cutom NDFD grids.

Q. In what formats can I access NDFD grids?
A. NDFD grids are encoded in WMO standard GRIB2 format. Please see the following to learn how to convert NDFD GRIB2 grids to shapefiles, netCDF, GrADS or GrADS, float files, and comma separated variable files.

Q. When will NDFD grids become official products?
Q. How frequently are the updates to the NDFD gridded data made available?
Q. Where can I find NDFD verification scores? (
Q. Where in NDFD do I find information on past weather?
A. Past Weather

Q. At what times are NDFD forecasts updated? What can I do if they are missing?
Q. Why are there sometimes holes in the NDFD mosaics?
Q. Why do I sometimes see unnatural discontinuities in the NDFD grids?
Q. Where can I find information on the weather text strings in NDFD grids?
A. Section 2 of

Q. Why do weather types appear in the grids that are not defined in the GRIB documentation?
Q. How can I find out about upcoming technical workshops concerning NDFD?
A. Please see

Q. How much does it cost to obtain NDFD forecasts?
Q. When will Marine forecast grids become available in NDFD?
Q. When will forecasts for Alaska and Hawaii become available in the NDFD?
Q. How can I access a forecast for a specific date and location?
A. NDFD graphical forecasts are posted on the web. You can access the latest NWS text forecasts for any point by clicking down to the local forecast office web pages from these graphics of the national scale forecasts. In addition you can download the NDFD predefined sector of interest to your laptop, then you can use degrib's probe routine (see tutorial) to querry a given lat/lon, just using your laptop.

Q. Why are the graphical forecasts on the national, regional, and state graphics on sometimes inconsistent with those available on the local forecast office web pages?
Q. How can I convert the NDFD girds from GRIB2 format to GIS files?
A. See Convert to ESRI shapefiles, and Convert to ESRI spatial analyst.