The increased availability of high resolution spatial data and improved usability of geographic information system (GIS) software has helped move GIS applications from research to operational mode. The NWS FLDVIEW application is the National Weather Services' flood forecast mapping application. It was developed by the Office of Hydrologic Development using ESRI's Arcview software with the 3-D Analyst and Spatial Analyst extensions. With the appropriate GIS data and a water surface profile (deterministic or probabilistic) of the mapping area, FLDVIEW produces a binary raster of the areal extent of flooding. This paper presents an overview of FLDVIEW along with the results of it's application to the Juniata River in the vicinity of Lewistown, Pennsylvania.