The WFO Nashville Hydrologic Service Area includes two major river systems, the Tennessee and Cumberland, which drain eighty percent of the land surface of Tennessee. The Tennessee River is formed at Knoxville, Tennessee by the confluence of the French Broad and Holston Rivers. About 48 miles west of Chattanooga, the Tennessee River leaves Tennessee to flow slightly more than 200 miles across northern Alabama and the northeast tip of Mississippi. The Elk River is the principle tributary in this reach. At the point where Alabama, Mississippi, and Tennessee come together, the Tennessee River turns north to flow some 150 miles across Tennessee into Kentucky. The major tributary in this reach is the Duck River.

The Cumberland River enters Tennessee just north of Celina in Clay County. From that point the 694-mile long river flows generally southwest to Nashville, Tennessee, and from there it turns northwest and flows into western Kentucky, 58.5 miles upstream from the confluence of the Ohio and Mississippi Rivers. The Cumberland River Basin lies entirely within the states of Kentucky and Tennessee and has a total area of 17,914 square miles, of which 10,695 square miles (sixty percent) are in Tennessee.

WFO Nashville is responsible for 22 river forecast and data points across its HSA, and issues the following hydrologic products:

Cumberland Basin Outlook
Cumberland Lake Stages and Forecasts
Daily River and Lake Summary (SHEF coded)
Daily River and Reservoir Summary
Hydrologic Outlook
National Flood Outlook
Tennessee Basin Flood Outlook

There are two National Weather Service River Forecast Centers that support the Nashville Hydrologic Service Area. The Lower Mississippi River Forecast Center provides river stage and crest forecasts for the river forecast points within the Tennessee River Basin. The Ohio River Forecast Center provides river stage and crest forecasts for the river forecast points within the Cumberland River Basin.

River stage information and NWS river forecasts are based, to a great extent, on data from U.S. Geological Survey stream-gaging stations. The USGS operates most of its stream-gages on a cooperative basis with other federal, state, and local agencies that fund the operation of individual gaging stations. Reductions in stream-gaging program funds due to budget cuts from USGS or cooperating agencies usually require that some stations be shut down or discontinued. Often such discontinuances adversely affect the NWS river monitoring and forecasting program.

For more information, see these hydrology related links:

Stream Gaging and Flood Forecasting
Streamflow Information for the Nation
U.S. Geological Survey
Flooding Safety

Please direct questions or comments about the hydrologic services program to Mike Murphy, Service Hydrologist, National Weather Service Office, Nashville, Tennessee.