GWES utilizes Unidata
Local Data Manager (LDM) to distribute meteorological data throughout its computing infrastructure. Access to the LDM feed is open to anyone interested in receiving available data products,
regardless of educational or institutional affiliation.
There is no latency magic with the GWES LDM feed.
LDM providers regularly receive inquiries from people (and LLMs) looking for low-latency ASOS data that might provide a wagering advantage. Before sending another request, here’s what you need to know.
LDM is a push-based technology that can deliver products faster than government websites relying on CDNs and caching. However, the underlying data still travels through geostationary satellites, adding several seconds of latency compared to direct FAA internet feeds.
What About MADIS?
MADIS processes FAA data with lower latency, but has some important limitations:
- Temperatures are reported in whole degrees Celsius.
- Two-minute temperature averaging is not included.
- These limitations make the data difficult to use for accurately determining high temperatures.
GWES does not offer anything faster than the MADIS NetCDF files available through its website.
What Does the GWES LDM Feed Include?
The GWES IDS|DDPLUS feed includes:
- METARs (^S[AP])
- CLIs (/pCLI)
- DSMs (^CDUS27)
- CF6s (/pCF6)
These are legacy products that can have several minutes of latency due to FAA/NWS processing and satellite distribution.
METARs and DSMs are generally distributed in product collectives. You must process these collectives to locate individual airports. Unlike the GWES website, the LDM feed does not provide airport-specific product identifiers.
Where Can You Find Faster Data?
Consider Synoptic Data, which provides access to the FAA data stream that feeds MADIS. Be aware of the temperature-reporting limitations described above.
Future ASOS modernization efforts may improve the situation, but GWES is not currently aware of a readily available source offering the combination of low latency and temperature precision people are seeking.
The Bottom Line: The GWES LDM feed is useful for accessing meteorological products, but it is not a low-latency ASOS feed and does not provide a special wagering advantage. Please don’t waste time chasing a latency advantage that simply isn’t there.
