National Weather Service United States Department of Commerce

Winter Storm Impacting the Central and Eastern U.S.; Another Winter Storm Moves into the West

A strengthening winter storm with trailing cold front will continue to progress across the central U.S. today then the eastern U.S. on Wednesday. Areas of heavy snow, severe thunderstorms, record high temperatures, high winds, and critical fire weather are expected due to the storm. Another storm system is likely to spread heavy rain and snow with strong winds across the West later this week. Read More >


Software Implementation

Configuration Information for
receiving data from the

Software Implementation Minimum Requirements


  1. An active TCP/IP connection to NWS with at least T1 (1.5 Megabits/sec) available bandwidth
    • NOTE: Contact for installation of a connection is: Julie Hayes, Phone: 301-713-0864 ext 120
  2. The following network configuration should be coordinated with the NWSTG:
    Interface configuration on OPSnet link
    Routing configuration including:
    • LDM receiver IP address(es) and fully qualified domain name(s)
      LDM server Virtual IP
    Access-lists and/or Firewall permits

  3. A computing platform capable of receiving 35 Gigabytes of RPCCDS product data files per day.

RPCCDS Data Stream

All available RPCCDS product data is delivered in bzip2 compressed 'tar' archive files named as wsr88dHHMM#.tbz2 containing the actual product data files with relative path structure. Archive contents are uniquely identified using directory path components formatted as "DC.radar/DS.ptype/SI.cccc/sn.####" (see: RPCCDS Product Files )


The RPCCDS product data is delivered in 10 second intervals upon receipt at the NWSTG server. RPCCDS subscribers should choose a computing platform with the operating characteristics consistent with their particular data processing requirements. There are no product retransmissions. Therefore, RPCCDS product data files missed will need to be individually pulled from the NWS ftp server farm ( ) to obtain any missing product data. The description of the product identifiers and the radar site location list are contained in the  RPCCDS Product Files  for FTP. It is the responsibility of the RPCCDS subscriber to detect when and if this should be necessary.

    • HHMM# is the archive file creation timestamp and sequence number
    • DC.radar is the relative lead directory path component for the radar product data file,
    • DS.ptype is the NEXRAD product type identifier (see: RPCCDS Product Files )
    • SI.cccc is the four character alphabetic site identifier code designation (see: RPCCDS Product Files )
    • sn.#### is a four digit product file sequence number for each filename of the product stored.

Receiver-side Software

  • The NWS requires the use of Unidata's Local Data Manager (LDM) software which is available for download from Unidata.


    Software Configuration Procedures


      • Obtain the LDM receiver software for your receiver platform and Operating System from Unidata.
      • Perform the LDM installation procedure
        • NOTE:   Although it does not require administrative privileges to install or run the LDM application software, some recommended configuration procedures will require administrative privileges on Unix systems (e.g, the /etc/services port setting, symbolic links in protected subdirectories, etc.).
      • LDM server address: &nbsp
      • LDM data feed type: FT27
      • The etc/ldmd.conf file has the following line commented out:
        #EXEC "rtstats -h"
    1. Since this is a private implementation, the following line needs to be added:
      REQUEST &nbsp EXP|FT27 &nbsp "^wsr88d[0-9]*\.tbz2" &nbsp
      • The etc/pqact.conf file has the following lines added:
        FT27 &nbsp ^(wsr88d.*)
        FILE &nbsp -overwrite &nbsp -close &nbsp /var/opt/ldm/NEXRD3/incoming/\1
      • NOTE:   You would configure the path components according to your actual downstream LDM receiver file system configuration.
      • Start up configuration
      We recommend the following start up settings verses the default 3600 seconds, especially if you are using a T1 connection:

      Example invocation:
      • ldmadmin start -o 200 (this configuration allows long latencies but prevents old data from being sent) or
      • ldmadmin start -m 210 (this configuration limits latencies to 210 seconds) or
      • ldmadmin start -o 200 -m 210 (this configuration does both)