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09 Jan 2001 Update: The NOAAPORT datastream began carrying unencrypted NEXRAD data for all radar sites at about 14 UTC this morning. If you're running McIDAS-X 7.704 and have access to a remote server with the NEXRAD datasets, you can list the radar sites available in each of the datasets by using the ID=LIST keyword in your IMGLIST commands. For example, the table below shows the number of radar sites that the SSEC Data Center was receiving for each of the datasets when the table's commands were run at 17 UTC today.

Command Number of Sites
(all six datasets above were receiving 151-154 sites by mid-January)

(The NEXRAD products listed in the middle and bottom tables (labeled "PRODUCTS ADDED AFTER AWIPS BUILD 4.3.3 IS IMPLEMENTED" and "PRODUCTS ADDED AFTER AWIPS BUILD 5.X IS IMPLEMENTED", respectively) of http://www.nws.noaa.gov/tg/rpccds.html are not yet available on NOAAPORT.)

02 Jan 2001 Update: The NWS announced today that unencrypted NEXRAD data on NOAAPORT is not yet available and that the current plan is "to remove the encryption of the NOAAPORT radar products no later than January 10, 2001".

30 December 2000


The National Weather Service's NEXRAD Information Dissemination Service (NIDS) agreement with private vendors ends 1 January 2001. Beginning on that date, NEXRAD data will be available free-of-charge via the NOAAPORT datastream, and therefore, to most of the McIDAS community.

The McIDAS-X changes needed to list, display and copy NEXRAD data are included in Fastrack version 7.704. You must install and run 7.704 if you want to use NEXRAD data, as it contains the new NEXRAD servers and image enhancements, and the command modifications made to allow and/or simplify use of NEXRAD data.

The basics of listing, displaying and copying NEXRAD data should work satisfactorily with version 7.704. There are known limitations in using NEXRAD data with other image commands. For example, IMGREMAP does not work with NEXRAD data and IMGPROBE gives "MISSING" as the scan time for all satellites. Fixes for those problems and improvements to make other image commands work better with NEXRAD data will be provided in later Fastrack releases.

We also expect that other changes may be necessary because we could not perform our testing in an environment even remotely similar to the one that will occur when the full suite of NEXRAD data (154 radar sites generating up to 15 products every 5-10 minutes) becomes available starting 1 January. Because of the NIDS contract that runs through 31 December, the NWS was able to supply only a very limited test dataset that consisted of just one radar site (ARX - La Crosse, WI) and only four products (base reflectivity, base radial velocity, composite reflectivity and storm total precipitation).

Using NEXRAD Data in McIDAS-X

Once version 7.704 (or later) is installed and you've run the specified DATALOC command, you will be able to access and use NEXRAD data. A new keyword, ID=, was added to the IMGCOPY, IMGDISP, IMGLIST and IMGPROBE commands in version 7.704. This ID= keyword is used to select the desired radar site. If you don't specify ID= when requesting data from a NEXRAD dataset, you'll get the first image that matches your search conditions (and that image probably won't be from the desired radar site).

The 154 NEXRAD radar sites can be listed using commands like STNLIST TYPE=N CO=US or STNLIST TYPE=N ST=NY. Use commands like STNLIST TYPE=N RADIUS=124[NMI] to list the NEXRAD stations closest to a feature on a satellite image. Also use the STNPLOT command with the TYPE=N keyword to plot NEXRAD stations on a frame.

Nine new enhancements (BREF.ET, CREF.ET, LREF.ET, PRE1.ET, PRE3.ET, PRET.ET, RVEL.ET, TOPS.ET and VIL.ET) for the various NEXRAD products were included in version 7.704.

The IMGDISP command was modified in 7.704 to read context files named IMGDISP.CORE, IMGDISP.SITE and IMGDISP.USER. The context files contain predefined products to make it easy to automatically load the correct enhancement and add other features when a NEXRAD (or any type of) image is displayed. Each predefined product consists of a name followed by a list of keywords to run when an IMGDISP command that requests the product is run from the command line.

An IMGDISP.CORE file that contains two predefined products for each of the 15 NEXRAD product types is supplied in version 7.704. Users can change the settings of the products in IMGDISP.CORE and/or create their own products by copying IMGDISP.CORE to their $HOME/mcidas/data or another MCPATH directory, renaming it to IMGDISP.USER, then editing the existing products and/or adding new ones. (As with other command context files, IMGDISP.USER overrides IMGDISP.SITE, which overrides IMGDISP.CORE.)

You can override a keyword setting in a predefined product by specifying the keyword (with the desired value) in the command line. You can also add keywords that aren't part of the product definition by specifying them in the command line. Click the links below to see the output generated by running IMGDISP with the ID=ARX keyword that overrides the ID=MKX setting in four of the predefined products in IMGDISP.CORE.

You can simplify creation of any sophisticated image display by making it a predefined product in your IMGDISP.USER file. Therefore, this new IMGDISP feature is useful for other non-NEXRAD image displays as well. Click here to see IMGDISP.CORE so you can preview it before installing McIDAS-X 7.704 or later.

Additional Information

See http://www.nws.noaa.gov/oso/noaaport.html for a listing of the 15 NEXRAD products that are expected to be available via NOAAPORT beginning 1 January. (The 15 products are those in the top two sections, minus the Radar Coded Messages, Digital Precipitation Array, and Free Text Messages, which are not available as images.)

See http://www.nws.noaa.gov/oso/rpccds.html for information about the Radar Product Central Collection Dissemination Service (RPCCDS), which becomes operational with the termination of the NIDS agreement on 1 January.

Note to users of the SSEC Data Center:
Once the SSEC Data Center is able to successfully file and serve the NEXRAD data (sometime after 1 January), the Data Center will send an email with the server, group name and the DATALOC command to enter. As stated above, you *must* be running McIDAS-X 7.704 or later to use the data. (Click here to see the message, sent 09 January 2001.)

Note to McIDAS-XCD sites:
Because the NEXRAD data will be available via NOAAPORT, all McIDAS-XCD sites that receive the NOAAPORT broadcast will be able to decode, file and serve the data beginning 1 January 2001. A separate email message with instructions for obtaining and installing the needed McIDAS-XCD changes will be sent to -XCD site coordinators. (Click here to see the messages, sent 30 December 2000 and 09 January 2001.)