The National Weather Service (NWS) has entered a new era in the production and dissemination of weather information and services to the nation. No longer are textual forecasts the primary medium of dissemination, but digital databases of current weather conditions and official forecasts are now available to the public, commercial entities, academic institutions, and government agencies. These databases, built from grids prepared by NWS meteorologists across the country, contain sensible weather elements, such as maximum and minimum temperature, probability of precipitation, and weather. Individual grids are collected at NWS headquarters, where they are combined and then incorporated into the National Digital Forecast Database (NDFD). Portions of the NDFD are disseminated via the World Wide Web (WWW) using both Digital Weather Markup Language, a NWS-developed Extensible Markup Language dialect, and Geography Markup Language (GML), an Open Geospatial Consortium (OGC) standard. The two data feeds are provided in an operational and experimental status respectively.

GML is a specification recommended by the OGC for creating special-purpose markup languages to disseminate geospatial data. GML follows a strict set of rules that make automated processing efficient which aids in sharing data. To transfer the GML encoded NDFD data, the NWS uses web services that employ a client and server architecture. By using GML and web services to provide its official digital forecast, the NWS is better positioned to serve the weather needs of the geospatial community and the decision makers that use its products.