The National Weather Service (NWS), under the National Oceanic and Atmospheric Administration (NOAA), provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy. The hydrology and water resources component of this mission relies on 13 River Forecast Centers (RFCs) to serve as centers for hydrological expertise, using hydrologic, hydraulic, and hydrometeorological models. Weather Forecast Offices (WFOs) located in 122 communities, working closely with the RFCs, coordinate with local emergency and water managers to disseminate forecasts and warnings to the local areas they serve. The National Center for Environmental Prediction (NCEP) provides meteorological forecast guidance.

As a direct result of “The Great Midwest Flood of 1993”, during the past 15 years the NWS implemented its Advanced Hydrologic Prediction Service (AHPS), which provides a range of enhanced water forecasts and information. More recently, a 2003 Government Accounting Office study of fresh water supply identified water shortages as concern throughout the country. Recent findings on the effects of climate change on water resources by the International Panel on Climate Change (IPCC) Regional Assessment of Vulnerability for North America (Shriner et al., 1998) concluded that water is a linchpin that integrates many geographic subregions and economic/social/ecological sectors of North America. It stated further, “The quantity and quality of water are likely to be directly affected by climate change.” In order to address the ever increasing needs of water resource forecasting from short to longer range time scales, the NWS is undertaking an ambitious program to build on AHPS and enhance and expand the hydrologic products and services to serve the Nation's increasing need for integrated water resources. Key elements of the enhancements that will eventually be incorporated across the country include: (1) implementing an operational modern modeling environment called CHPS (Community Hydrologic Prediction Service) based on a service oriented architecture, (2) a seamless suite of ensemble forecasts ranging from hours to years allowing users to produce a variety of probabilistic products, (3) objective coupling of short, medium and longer range weather and climate models to operational hydrologic models , (4) smaller space and time steps, (5) new data sources, (6) improved collaboration with Federal, State and local partners through a new focus called “Integrated Water Resources Science and Services “ (IWRSS), and (7) and new products and services to meet the increasing needs for water resource forecasts and information.