Developing Skill Assessment and Performance Metrics for the National Ocean Service's Operational Storm Surge Model Forecasting Systems.

The Coast Survey Development Laboratory at NOAA's National Ocean Service develops, tests and transitions to operations a series of storm surge model forecast products. These include continuously operating Extratropical Surge and Tide (ESTOFS) system that covers the majority of US seaboard in Pacific and Atlantic basins, as well as Hurricane Surge On-Demand (HSOFS) system currently deployed in the US East/Gulf Coast and Caribbean. During a development phase, numerical models traditionally go through a rigorous hindcast skill assessment against coastal water level observations and also peak inundation measurements (high-water marks) associated with historical inundation events. However, there is a need to evaluate model guidance in the operational setting, in order to provide end users with complete metrics of model performance in nowcast/forecast mode as a function of region, season, and forecast lead time. In addition, such metrics are an integral part of coastal water level data assimilation algorithms that are implemented for both tropical and extratropical guidance. We will discuss our general approach, development and upcoming applications including multi-model guidance, and offer some preliminary analysis for discussion.