Decomposing Sources of Error in National Water Model Flood Forecasts

The NOAA National Water Model currently provides real-time hydrologic forecasts for over 2.7 million river reaches in the contiguous U.S. and now Hawaii. These forecasts are critical components of a model-based guidance system used by forecasters for the issuance of flood and flash flood watches and warnings. Despite the spatial fidelity offered by the NWM, there are many challenges in using these forecasts in real-time decision making. One of those major challenges in understanding the sources of error entering into the forecasting system. This talk will provide a contextual overview of error sources in several major flood and flash flood event types. A quantitative analysis of different error sources will also be provided for a selection of recent significant flood events. The goal of this analysis is to provide forecast interpretation context to those using forecasting tools like the National Water Model for key decision support activities.