Three Day Mainstem River Forecast Verification

The North Central River Forecast Center (NCRFC) has been verifying three day mainstem Mississippi River forecasts since January 1981. For a majority of the locations, three day forecasts are prepared daily throughout the year. Several locations are forecasted daily only during the navigation season. Monthly statistics include the mean error, variance, standard deviation, and mean absolute error. Also documented are the number of times the forecast error exceeds 1.5 feet for the first day forecast? if the observed stage is above flood stage; the total number of forecasts processed; and the number of observed stages and first day forecasts above flood stage. The approach is simple, and consists of canpiling a data base fran which one might evaluate the three day forecast accuracy at various forecast locations along the mainstan Mississippi River. In June of 1987 the number of stations verified expanded from five on the Mississippi River to 13 on both the Mississippi and Illinois Rivers (Table 1). 1988 NWS (National Weather Service) NWC (National Water Center) Library Public Domain 1931