Floods are by far the most devastating of all weather-related hazards in the United States. The National Weather Service (NWS) is charged by Congress to provide river and flood forecasts and warnings to the public to protect life and property and to promote the nation’s economic and environmental well-being (such as through support for water resources management). As part of a modernization of its technologies and organizational structure, the NWS is undertaking a thorough updating of its hydrologic products and services and the activities that produce them. The National Weather Service Modernization Committee of the National Research Council undertook a comprehensive assessment of the NWS’ plans and progress for the modernization of hydrologic and hydrometeorological operations and services. The committee’s conclusions and recommendations and their related analysis and rationale are presented in this report.