National Weather Service United States Department of Commerce


The National Weather Service as it is known today has been forecasting the nation's rivers for over 100 years. As technology and the science of hydrology have changed and progressed significantly over this time period, so have the National Weather Service’s river forecasting capabilities. Initially only the major navigable rivers were forecast using travel time and crest relationships between stations. In the 1930’s significant advances were made by Sherman in 1932 with the concept of the unit hydrograph and in 1938 by Snyder with the development of the synthetic unit hydrograph. With these and other advances the ability to provide better, more timely and accurate river forecasts had begun. In addition to the scientific advances, technological advances have allowed more complicated forecasting models to be used, allowed for real time data collection and increased frequency and quantity of forecasts.