Chesapeake Bay Operational Forecast System (CBOFS)

Notice of NOS OFS product changes

Effective on or about August 2024, the names of the model output files will officially be transitioned to the following format:

  • Stations: OFS.tCCz.YYYYMMDD.stations.[nowcast|forecast].nc
  • 2-D surface field output: OFS.tCCz.YYYYMMDD.2ds.[n|f]HHH.nc
  • 3-D field output: OFS.tCCz.YYYYMMDD.fields.[n|f]NNN.nc
  • 3-D field output on a regular grid: OFS.tCCz.YYYYMMDD.regulargrid.[n|f]NNN.nc
    • Where:
  • OFS refers to the name of the model (e.g. cbofs, sfbofs, leofs)
  • [nowcast/forecast] or [n/f] denotes either the nowcast or forecast results
  • YYYYMMDD refers to the date of the model run
  • CC refers to the cycle of the day (e.g. 06, 12)
  • HHH is the nowcast or forecast hour (e.g. 001, 002)

Starting April 1, 2024, model output files with both the existing and the new file formats will be made available here for users to update and test code used to automate the download of the model output. As August 2024 draws near, this notice will be updated with the exact date of the transition.

(Please click on the map pins below to access the time series plots)

For decades, mariners in the United States have depended on NOAA's Tide Tables for the best estimate of expected water levels. These tables provide accurate predictions of the astronomical tide (i.e., the change in water level due to the gravitational effects of the moon and sun and the rotation of the Earth); however, they cannot predict water-level changes due to wind, atmospheric pressure, and river flow, which are often significant.

To better serve maritime user community, an upgraded three-dimensional version of the Chesapeake Bay Operational Forecast System (CBOFS) was developed by the NOAA/National Ocean Service/Office of Coast Survey in a joint project with the NOAA/NOS/Center for operational Oceanographic Products and Services (CO-OPS) and the NOAA/National Weather Service/National Centers for Environmental Prediction (NCEP) Central Operations (NCO) using Rutgers University's Regional Ocean Modeling System (ROMS). CBOFS generates water level, current, temperature and salinity nowcast and forecast guidance four times per day. Aerial animations of the whole Chesapeake Bay as well as time series at particular stations or points of interest are available for over 58 locations for the five parameters (water level, currents, temperature, and/or salinity).

CBOFS runs on NOAA's High Performance Computers (HPC) in a new Coastal Ocean Modeling Framework (COMF) developed by CO-OPS. As a result, CBOFS has direct access to National Weather Service operational meteorological products that it needs to run reliably.

The higher resolution and three-dimensionality of the new CBOFS along with the added current nowcast and forecast information and the additional reliability of running at NOAA's HPC will further assist U.S. port authorities and mariners in efficiently navigating the Chesapeake Bay without compromising safety.

For more detailed information about CBOFS, please click here.

For more information about ROMS, please click here.

Disclaimer: The Chesapeake Bay Operational Forecast System (CBOFS) has been implemented by NOAA's National Ocean Service (NOS) to provide the maritime user community with short-term predictions of water levels, water currents, water temperatures and salinity of the Chesapeake Bay. CBOFS uses a numerical hydrodynamic model to generate the nowcast and forecast information; therefore, they should be considered as model-generated nowcast and forecast guidance. For more detailed information related to the OFS disclaimer, please visit at the Disclaimers web page.