Development of Extratropical Surge and Tide Operational Forecast System (ESTOFS)

The Coast Survey Development Laboratory (CSDL) of the National Ocean Service (NOS) and the Environmental Modeling Center (EMC) of the National Centers for Environmental Prediction (NCEP) have collaborated to establish an Extratropical Surge and Tide Operational Forecast System (ESTOFS) for the Western North Atlantic basin. The hydrodynamic model employed for ESTOFS is the ADvanced CIRCulation (ADCIRC) finite element model. The ESTOFS will be implemented operationally by NCEP Central Operations (NCO) to provide forecasts of surge with tides, astronomical tides, and sub-tidal water levels (the isolated surge) throughout the domain. The ESTOFS combines the surge with tides and utilizes unstructured grids, which can provide higher resolution at the coast. The ESTOFS is also designed to provide the surge with tides to WAVEWATCHIII (WW3) for coupling waves with coastal water levels. Therefore, ESTOFS set-up is designed to follow WW3: it uses the same Global Forecast System (GFS) surface forcing and has the same forecast cycle and length, and will run concurrently at NCO. The model results are compared with observations at 62 stations using NOS' standard skill assessment software. The skill assessment focuses on the performance of the model in simulating water levels in two model run scenarios: the hindcast, and the semi-operational forecast. As for the results of skill assessment, the model's water level forecasts are of sufficient accuracy for operational implementation.