Frequently Asked Questions
  1. Can you recommend a vendor I can contact?

    While we can not recommend a specific vendor, we maintain a list of vendors on the WIFS web page. Point your web browser to http://www.aviationweather.gov/wifs and click on the Support tab.

  2. I contacted the vendor for support and we can not afford their services as we have no budget for the proposed estimated cost. Is there an alternative for me?

    One option is to develop your own application to download and visualize the data. Another option is to use freely available packages such as Gempak or Grads (see FAQ #4). For more information on downloading and data, please reference the WIFS User’s Guide on the web site. Point your browser to http://www.aviationweather.gov/wifs and click on the Documents tab. There you will find the User’s Guide. The data retrieval process is described in Chapter 5 and the GNU Wget utility is described in Appendix B.

  3. My platform is over 10 years old. Will it work?

    It depends on your operating system and the version of the Gnu Wget tool installed on your system. Your platform must support a version of Wget that manages certificates on Secure Socket Layers (SSL) and can access WIFS through the HTTPS protocol.

  4. I don't want to use a vendor. What free software do I need to access WIFS and display the information?

    For instructions on acquiring the data, please reference the WIFS User’s Guide. Point your browser to http://www.aviationweather.gov/wifs and click on the Documents tab. The data retrieval process is described in Chapter 5 and the GNU Wget utility is described in Appendix A. An alternative retrieval method is to point your web browser to http://www.aviationweather.gov/wifs/data, log in with your WIFS credentials, and download the file(s) of interest via your web browser. Both of these options are described in Appendix A (Use Case) of Appendix B (Wget) in the User’s Guide.

    For displaying the data, you’ll need the ability to decode and then render GRIB2 and BUFR formatted files. There are several freely available packages that perform this function:

    GEMPAK: http://www.unidata.ucar.edu/software/gempak/

    GRADS: http://www.iges.org/grads/

    NCEP decoding libraries (no display functions): http://www.nco.ncep.noaa.gov/pmb/codes/

    Note that none of the above packages are uniquely tailored to support an “off the shelf” WIFS solution. You will have to set up and configure the software without support.

  5. When I connect nothing happens.

    If you are using vendor-supplied software please contact your vendor for technical support. Otherwise please consult the User Troubleshooting Guidelines in the WIFS Users Guide available online. Point your browser to http://www.aviationweather.gov/wifs and click on the Support tab.

  6. I can pull the data in but nothing is displayed.

    If you are using vendor-supplied software please contact your vendor for technical support. Otherwise please compare the size of the downloaded file with that on the WIFS web site. To do this point your browser to http://www.aviationweather.gov/wifs/data and enter your credentials in the login box. Then point and click on the folder of interest, find your file and take note of the size. If the size is different something went wrong during the download. Please download the file again. If the file size is the same please download a different file and see if it is displayable. If it is not displayable, the problem is likely in the display software. If it is displayable, the original WIFS data file may be corrupt and you are asked to notify the WIFS Help Desk.

  7. How do I download all the files from a folder?

    To download the entire contents of a directory simply add the recursive (-r) switch to your Wget command and point the URL to a directory name instead of a file. See the example below. The “no-directories” (-nd) option tells Wget to store only the files and not the directory structure.

    wget --user=<user_id> --password=<password> --no-check-certificate -r -nd https://www.aviationweather.gov/wifs/data/OPMET-ROLLING/

    For more information on how to use Gnu Wget please visit the Gnu Wget web page at http://www.gnu.org/software/wget.

  8. How do I only download the latest set of files and not the whole folder every time?

    If you are using vendor-supplied software please contact your vendor for technical support. The vendor designates the download setup. It’s up to their scripts to select only the current files, or update the downloaded files with latest data.

    OPMET data is continuously updating so files need to be downloaded and updated accordingly. In this case, it’s best to set up downloads so they continue from the last byte that was downloaded.

    Other files such as BUFR and GRIB2 data are made available only when the complete file is available. Care should be taken to make sure scripts know what has been downloaded and not download those files again such as using the -nc (no clobber) option to wget.

  9. How long should it take to pull in the files. It appears that the system is taking forever.

    Transfer speeds are very site specific. Internet connections must be fast enough to handle the amount of data needed for the application.

    In designing WIFS, most data files are partitioned so that they are not too large to be downloaded. Care was taken to provide only the necessary data and eliminate redundant or duplicate data. Even with that, these data files aren’t small and sites with slow or intermittent Internet connectivity can have significant delay in downloads.

    For more information on download times, see Information Paper 42 (IP/42) at:

    http://www.bangkok.icao.int/cns/meeting.do?method=MeetingDetail&meeting_id=78

  10. Do I need to uncompress the files before I can display them?

    The WAFS products are already compressed or encoded to reduce size. If you are using software provided by your vendor, the files will be automatically decoded and processed.

    OPMET data has products in METAR (surface observations), TAF (aerodrome forecasts) and SIGMET (significant weather forecasts) formats. Gridded data are in GRIB version 2 format. Significant weather (SigWx) are in BUFR format. All formats are defined by WMO (World Meteorological Organization) standards. Here are some links to formats and coding:

    http://www.wmo.int/pages/prog/www/WMOCodes.html (specifically look at volume 1.2 on binary codes for GRIB and BUFR)
    http://www.nco.ncep.noaa.gov/pmb/docs/grib2/ (NCEP documentation on GRIB2)
    http://www.lima.icao.int/eDocuments/MET/OTHERS/SigmetGuide2010.pdf (CARSAM ICAO SIGMET guide)

  11. I am missing OPMET files. What happened?

    If you are using vendor-supplied software, please contact your vendor for technical support.  Otherwise, please check the WIFS web site to see if the data is up-to-date.  Browse to http://www.aviationweather.gov/wifs/data and use your WIFS credentials to log on.  Once you are logged on click on the OPMET-MINUTE folder.  These files are updated every minute.  If you see up-to-date files on the web site, then the problem is likely related to something on your system (network connection, incorrect download command, etc.).  Please retry your download command.  If it fails again, send the command you are using along with any diagnostic output including errors to wifs.admin@noaa.gov.  You can also reference the Troubleshooting section in the WIFS Users Guide for help.

  12. Why are there multiple OPMET folders and files - which one should I use?

    The OPMET data is offered in several different file formats due to vendor request.  The raw OPMET records are the same in every file.  What is different is the time window that is covered (1 minute, 5 minutes, 1 hour, etc).  For details on what each OPMET file contains please reference the WIFS Users Guide by browsing to http://www.aviationweather.gov/wifs and clicking on the Documents tab.

  13. How long does it take to download the data off WIFS?

    The data files on WIFS vary greatly in size. The typical hourly OPMET file is around 1MB (1 million bytes) in size. The typical or GRIB 2 file is around 2-3MB in size. BUFR and PNG files are smaller. Typical high speed Internet connections (>5Mbit/sec) should download these files in just a few seconds. Slower internet connections can download the files but it may take several minutes depending on the connection speed.  The minimum recommended download speed for using WIFS is 64 kbps (kilobits per second)

  14. My ISP is only 64KB. What should I do?

    The data on WIFS have been organized such that each file is a reasonable size and downloading on a slow Internet connection shouldn’t be a problem. Typical downloads should still occur within a couple of minutes. GRIB data files are somewhat largers but since these only come out once every size hours, they should affect routine operations. In addition, the vendor might have a solution to make sure GRIB file downloads don't affect the workstation performance. For more information about download times please reference Information Paper 42 (IP/42) on the following ICAO web site: http://www.bangkok.icao.int/cns/meeting.do?method=MeetingDetail&meeting_id=78.

  15. I have access to SADIS. Do I need WIFS?

    If you are a SADIS primary user, you may use WIFS as a backup data source. Go to the "Click Here to Register" on the home page to register for an account. See the WIFS User’s Guide under section 4.3B. Point your browser to http://www.aviationweather.gov/wifs and click on the Documents tab. There you will find the User’s Guide.

    As for use, SADIS and WIFS are organized slightly differently even though the content is almost identical. For information on the WIFS file structure and access details, see the WIFS Users Guide, Section 6 and supporting Appendices A-C. Check with the vendor for further assistance..

  16. I have access to WIFS. Do I need SADIS?

    If you are a WIFS primary user, you may use SADIS as a backup data source. See the WIFS User’s Guide under Section 4.3A and follow the procedures outlined for establishing a SADIS backup account. See the SADIS User’s Guide for details on the SADIS file structure and access; link provided in the WIFS User’s Guide under Section 4.3A

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