National Weather Service United States Department of Commerce

River Forecast Centers

The duties of the River Forecast Centers are to 1) Provide river and flood forecasts and warnings for the protection of lives and property, and 2) Provide basic hydrologic forecast information for the nation's environmental and economic well-being.

A sample river level forecast for a particular location. The blue curve represents the observed river level and how it has changed over time. The purple dots/line are the RFC's forecast for the river level into the future. The yellow, red and purple shading indicate various significance stages of flooding at that site.

Precipitation Forecasting

The process of forecasting rivers begins with the forecast of the rainfall expected over a period of time. Staff meteorologists prepare a full 5-day precipitation forecast to monitor developing systems.

Precipitation Analysis

Every hour staff meteorologists analyze Doppler radar products with measured rainfall from the local gage networks to determine the best estimate of actual rainfall over the region. This estimated rainfall is combined with the 12-hour forecasted rainfall to give the hydrologists an estimate on how much water can be expected to reach a river.

Headwater River Modeling

Heavy rainfall will impact any portion of the river, but the most sensitive areas during or immediately following rainfall are the small streams, tributaries, and headwaters that flow into the mainstem rivers. These watersheds react very quickly and cause hazardous flash flooding situations; however, these waterways can recede just as fast as they rise creating short term flooding conditions.

Mainstem River Forecasting

How river forecasts use runoff and time to reach to reach each forecast point.

Modeling river flow involves many pieces that must work together to create an accurate forecast. One such factor, soil moisture, is modeled to estimate how much of the rainfall will actually become runoff opposed to remaining in the soil. A second factor is the time it takes for the runoff to reach gage 'A'.

Once that is known, the water is routed to next gage (gage 'B') downstream to learn how much runoff and the time it takes to arrive. This flow then combines with the local runoff between gage 'A' and 'B' to create the forecast for gage 'B'. This process continues all the way downstream (e.g., 'A' to 'B', 'B' to 'C', 'C' to 'D', etc.).

Water releases operations from the various reservoirs by the Corps of Engineers, River Authorities, and Water Districts along rivers are also coordinated and incorporated into all forecasts. Additionally, the USGS provides accurate flow and stage observations during flood events for use with the forecasts.

Below is a map of the river forecast centers and their areas of responsibility. Click or select on image below or use drop down menu to go to any office.

Map of the 13 River Forecast Centers and their areas of responsibility.
Aklaska-Pacific RFC Northwest RFC California-Nevada RFC Missouri Basin RFC North Central RFC Lower Mississippi RFC Arkansas-Red Basin RFC Colorado Basin RFC West Gulf RFC Southeast RFC Ohio RFC Middle Atlantic RFC Northeast RFC

The RFC provides hydrologic guidance for time scales that vary from hours (flash flood guidance and support to Local Flood Warning Systems), to days (traditional flood forecasts), to weeks (snowmelt forecasts), to months (seasonal water supply) seen in the figure below.

Time scale for various River forecast Center forecasts/outlooks.

The RFCs are firmly committed to providing the best possible river forecast guidance to the customers. Improvements come in the form of expanded coverage and increased quality. Efforts are continuously underway to improve the process used to forecast flooding, spring snowmelt, and water supply volumes.