At a high level the flow of METAR data from ASOS sites at U.S. Airports
traverse the FAA networks to the NWS NWSTG/GATEWAY system. Once at
NWSTG/GATEWAY, essentially, the data is sent to TGFTP.nws.noaa.gov as well
as to the NCF, where the NCF uplinks the data to the SBN/NOAAPORT. UNIDATA
and other top-tier LDM/IDD sites with an SBN/NOAAPORT ingest system will
receive METAR data from the SBN/NOAAPORT and inject it into the LDM/IDD
network. Returning to the NWSTG/GATEWAY, they also send METAR data to
other WMO member countries at the same time they send the data to TGFTP and
NCF.
MADIS is different from the NWSTG/GATEWAY. Note MADIS originated on the
research side of NOAA (i.e. OAR ESRL/GSD per your weblink) and then a
version became operational at NWS/NCEP many years ago. MADIS also
collected various mesonets. From my understanding MADIS is no longer being
developed, instead the NWS is utilizing SynopticData
<https://synopticdata.com/>to acquire the various mesonets. I understand
SynopticData also connects with the FAA to acquire observational data via a
special agreement. You would have to check with the FAA (and I'm not sure
who it would be) to see if other private sector companies connect to the
FAA to receive METAR data.
I suspect the lowest latency will be obtaining data from TGFTP, followed by
an LDM feed from the IDD.
Some weather enthusiasts repurpose old satellite dishes from the 1980s or
1990s, originally used for satellite TV, for their own SBN/NOAAPORT
satellite ingest systems. This includes buying a NOVRA box, computer, etc
to ingest the data from the dish. This is an option to obtain METAR data
from the SBN and it would be slightly faster than the latency introduced by
the IDD (which is likely only a few seconds faster depending on how close
your connection is to a top-tier site). You could also set up a smaller
satellite dish (compared to the SBN/NOAAPORT dish) and use the Emergency
Managers Weather Information Network (EMWIN), which is supposed to include
METAR observations. I suspect the route of METAR data for EMWIN goes from
NWSTG/GATEWAY -> NESDIS -> GOES EAST/WEST satellites. Also, I believe
there is a terrestrial based EMWIN server if you don't want to set up a
satellite ingest system.
Gregg
On Tue, Mar 17, 2026 at 10:06 AM Thomas B <thms_brgg@xxxxxxxxx> wrote:
> Hi,
>
> Thanks for the pointer to tgftp.nws.noaa.gov — I'm currently polling it
> and it does seem to be one of the fastest publicly available HTTP sources
> for METAR.
>
> However, from what I've been reading, tgftp serves static files that are
> regenerated on a cycle (the MADIS documentation at
> https://madis.ncep.noaa.gov/madis_metar.shtml mentions data is "processed
> every 5 minutes"). So even with aggressive polling, there's an inherent
> delay of up to several minutes between the observation time and when it
> appears on tgftp.
>
> By contrast, the LDM/IDD network distributes METAR via push as soon as
> it's injected from NOAAPort/SBN. The LDM network troubleshooting docs (
> https://docs.unidata.ucar.edu/ldm/current/troubleshooting/networkTrouble.html)
> reference sub-second product latency as typical for well-connected IDD
> nodes.
>
> For my use case, that difference matters a lot — I need the lowest
> possible latency on METAR observations. So I'm really interested in getting
> an LDM feed rather than polling tgftp.
>
> I saw in the FAQ that non-academic users can sometimes arrange a feed from
> a willing upstream participant.
>
> Thanks again for your help.
> Le lundi 16 mars 2026 à 22:26, Charles Concodora <
> concodcw@xxxxxxxxxxxxxxxxx> a écrit :
>
> As far as I'm aware, tgftp.nws.noaa.gov has the lowest latency.
>
> On Mar 15, 2026, at 2:30 PM, Thomas B <thms_brgg@xxxxxxxxx> wrote:
>
> tgftp.nws.noaa.gov
>
>
>
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