The National Oceanic and Atmospheric Administration’s (NOAA) National Ocean Service has developed an experimental nowcast/forecast system over Galveston Bay using a modified version of the Blumberg-Mellor (1987) three-dimensional hydrodynamic model as discussed by Schmalz (1997, 2000). In addition, a one-way coupled fine resolution Houston Ship Channel model (Schmalz, 1997) has also been incorporated into the system. The nowcast component works directly from the PORTS universal flat file format (PUFFF) files, while during the forecast the NWS Aviation and Extratropical Storm Surge Models are used to provide the meteorological and Gulf of Mexico subtidal water level residual forcings, respectively. Early in 2004 the Galveston Bay experimental nowcast/forecast system will become formally operational.

Nowcast and forecast results have been assessed (Schmalz, 2001) over the one-year period April 2000 through March 2001 based on the NOS (1999) formal acceptance statistical criteria. For water levels, a majority of the targets were met and considerable skill was achieved in forecasting low water level events associated with winter cold frontal passages. Currents were more problematic, especially at Morgans Point at the head of the Bay, where rainfall/runoff flows exhibit considerable impact on currents within the Port of Houston. To improve the current response and to move towards an all weather capability, the following processes have been considered: 1) rainfall/runoff inflows from four major basins within the City of Houston, 2) overland flooding, 3) tropical storm and hurricane wind and pressure fields, and 4) surface waves.

The algorithms used to describe each of the above processes are first described. Next, the design and testing of the all weather nowcast/forecast system is presented. To conclude, broader operational issues and plans for such systems are outlined in the context of NOAA’s Coastal Storms Initiative.