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Degrib: NDFD Frequently Asked Questions (FAQ)

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.)

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. To learn how to use degrib to convert NDFD GRIB2 grids to shapefiles (click here), netCDF (click here), GrADS (click here or here), float files (click here), and comma separated variable files (click here).

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?

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. In addition to, you can register here. Along with release notes about degrib, you will recieve email notifications of any technical workshops that the authors of degrib know about.

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.

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    Page last Modified: January 28, 2005.
Degrib Questions? Arthur Taylor
NDFD Questions?
XML Questions? Paul Hershberg & John Schattel
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