McIDAS-XCD 2023.1 LDM changes for NOAAPORT NGRID feed (SCN 24-54)

The NWS has released the following Service Change Notice (SCN) pertaining to the NOAAPORT feed:
https://www.weather.gov/media/notification/pdf_2023_24/scn24-54_channel_realignment_to_SBN_aae.pdf

The original implementation date for this change was August 5, 2024. Due to extended severe weather, the implementation date was changed from on or about 1200 Coordinated Universal Time (UTC) August 5, 2024, to on or about 1200 UTC September 9, 2024.

SCN 24-54 announces that as part of efforts to improve data flow, the NWS will “migrate all grib, grib2, and bufr formatted data from the NMC channel to the NMC2 channel.” In particular, the grib, grib2, and bufr messages supplied over the HDS (also known as HRS) LDM feed type will be moving to the NGRID LDM feed type. For emphasis, the data itself is NOT changing, but is being moved from one location to another. However, if you have LDM REQUEST or pqact.conf entries that rely on HDS or HRS feed types, you must change the feed type to NGRID or ANY in order to continue filing the data.

Here are our recommendations for McIDAS-X 2023.1:
(Note: if you are running the beta version of McIDAS-XCD, please contact the McIDAS Help Desk for the updated instructions.)

1. On your McIDAS-XCD machine, open the /home/ldm/etc/pqact.conf file and examine the entries, specifically those involving the HDS/HRS and NGRID feed types.
  - - Search for the HDS or HRS entries.
```
       HRS ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN
                   - or -
       HDS ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN
```
      - If you do nothing, these lines will file HDS/HRS to the spool file until the NWS change is implemented.
      - After the change is implemented, if you have any of the following lines, you can either comment out the line with a ‘#’, delete the line, or keep it as is. After the change, LDM will no longer be filing this data via this entry as the data has moved to a different channel.
  - - - Search for the NGRID entry.

                             NGRID ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN

1. 1. - - If you do not have the NGRID line, add it to the /home/ldm/etc/pqact.conf file. (Note that the text should be separated by tabs.) Adding this line will guarantee that the data from HDS/HRS that has been moved to the NGRID feed type will be picked up and filed by the LDM.
        
        If you do not add this line, the NGRID feed type will not be filed to the spool file, and you will not receive the HDS/HRS data that is now being sent via NGRID.
1. Be sure to be aware of the change on the implementation date. NWS may revert their changes or you may need to make unexpected changes to receive the data. Carefully monitor the rollout and be prepared to take immediate action.
This ends the instructions for updating the LDM for SCN 24-54.

FAQ

Question: What about the SCN’s recommendation to change everything over to just use ANY?

SCN 24-54 states that “the NWS recommends that all users ensure their requests from NOAAPORT/SBN utilize the feed type of ANY rather than specific feed types such as HDS and NGRID.” However, after some consideration, we do not recommend using ANY in the feed type in conjunction with McIDAS-XCD 2023.1.

Question: Why don’t we recommend using the ANY feed type?

The recommended entries for the /home/ldm/etc/pqact.conf file in the -XCD Administrator’s Manual (https://www.ssec.wisc.edu/mcidas/doc/xcd_guide/current/install-8.html) with the added NGRID feed type added in Bullet Point 1 should now be:
```
         PPS|DDS|IDS ^.* PIPE /home/oper/mcidas/bin/ingetext.k NTXT
         NGRID ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN
```
For systems using the LDM CONDUIT feed type, an optional DMCOND Data Monitor was added in McIDAS-XCD 2020.1 (https://www.ssec.wisc.edu/mcidas/doc/xcd_guide/current/install-11.html). It is also recommended to create a separate spool file for the CONDUIT data, as doing both the CONDUIT and NGRID LDM feeds in the same spool file increases the tendency for dropped GRIB messages. In step 4 of “Creating a Separate Spool File for the CONDUIT decoder”, the entry for the /home/ldm/etc/pqact.conf file should be:
```
          CONDUIT ^.* PIPE /home/oper/mcidas/bin/ingebin.k NCON
```
Therefore, if you want to file the NGRID and CONDUIT feeds in separate spool files, lines with ANY as the feed type would be indistinguishable to tell McIDAS-XCD 2023.1 which circuit (NCON or NBIN) to use. For example:
```
          ANY ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN
               - or -
          ANY ^.* PIPE /home/oper/mcidas/bin/ingebin.k NCON
```
So, if you are not filing LDM CONDUIT data, this line would work:
```
          ANY ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN
```
However, if you are filing LDM CONDUIT data, it is recommended to have the following two lines in the /home/ldm/etc/pqact.conf file:
```
          NGRID|NNEXRAD ^.* PIPE /home/oper/mcidas/bin/ingebin.k NBIN
          CONDUIT ^.* PIPE /home/oper/mcidas/bin/ingebin.k NCON
```

McIDAS Man computer Interactive Data Access System

McIDAS-XCD 2023.1 LDM changes for NOAAPORT NGRID feed (SCN 24-54)

FAQ