NOAA and its partners have developed a new forecasting tool to simulate how water moves throughout the nation’s rivers and streams, paving the way for the biggest improvement in flood forecasting the country has ever seen. Launched today and run on NOAA’s powerful new Cray XC40 supercomputer, the National Water Model uses data from more than 8,000 U.S. Geological Survey gauges to simulate conditions for 2.7 million locations in the contiguous United States. The model generates hourly forecasts for the entire river network. Previously, NOAA was only able to forecast streamflow for 4,000 locations every few hours.