The Operational Forecast System (OFS) from NOAA

An Operational Forecast System (OFS) consists of the automated integration of observing system data streams, hydrodynamic model predictions, product dissemination and continuous quality-control monitoring. State-of-the-art numerical hydrodynamic models driven by real-time data and meteorological, oceanographic, and/or river flow rate forecasts form the core of these end-to-end systems. The OFS perform nowcast and short-term (0 hr. - 48 hr.) forecast predictions of pertinent parameters (e.g., water levels, currents, salinity, temperature, waves) and disseminate them to users.

Nowcasts and forecasts are scientific predictions about the present and future states of water levels (and possibly currents and other relevant oceanographic variables, such as salinity and temperature) in a coastal area. These predictions rely on either observed data or forecasts from a numerical model. A nowcast incorporates recent (and often near real-time) observed meteorological, oceanographic, and/or river flow rate data. A nowcast covers the period of time from the recent past (e.g., the past few days) to the present, and it can make predictions for locations where observational data are not available. A forecast incorporates meteorological, oceanographic, and/or river flow rate forecasts and makes predictions for times where observational data will not be available. A forecast is usually initiated by the results of a nowcast.

File Format

The files are in NETCDF format. Both NOAA and NASA provide tools for accessing NETCDF files:

Accessing Operational Forecast System Data on AWS

The OFS Forecast is stored in an Amazon S3 bucket in us-east-1 AWS region.

This bucket contains the ensemble forecast data organized by day.

You can use the AWS Command Line Interface to list a particular day in the bucket like this:


OFS Code Operational Forecast System Forecast Horizon Resolution
cbofs Chesapeake Bay 48 hrs 50m - 3km
creofs Columbia River Estuary 48 hrs 100m - 4km
dbofs Delaware Bay 48 hrs 100m - 3km
glofs Great Lakes 60 hrs 5 km
gomofs Gulf of Maine 72 hrs 700 m
leofs Lake Erie 120 hrs 400m - 4km
negofs North Eastern Gulf of Mexico 48 hrs 45m - 2km
ngofs Northern Gulf of Mexico 54 hrs 600m - 10km
nwgofs North Western Gulf of Mexico 48 hrs 60m - 3.5km
sfbofs San Francisco Bay 48 hrs 100m - 4km
tbofs Tampa Bay 48 hrs 100m - 1.2km

Construction of the path for particular OFS will access to the forecast data. To construct the path and filename substitute the following variables into the path templates below:


File Names Format File Type
nos.OFS.stations.nowcast.YYYYMMDD.tCCz.nc Station nowcast file (NetCDF) output
nos.OFS.stations.forecast.YYYYMMDD.tCCz.nc Station forecast file (netCDF) output
nos.OFS.fields.nHHH.YYYYMMDD.tCCz.nc Field nowcast file (NetCDF) output
nos.OFS.fields.fHHH.YYYYMMDD.tCCz.nc Field forecast file (NetCDF) output
nos.OFS.2ds.nHHH.YYYYMMDD.tCCz.nc Surface layer 2D Field nowcast file (NetCDF) output
nos.OFS.2ds.fHHH.YYYYMMDD.tCCz.nc Surface layer 2D Field forecast file (NetCDF) output
nos.OFS.met.nowcast.YYYYMMDD.tCCz.nc Surface forcing nowcast file (NetCDF) input
nos.OFS.hflux.nowcast.YYYYMMDD.tCCz.nc Surface flux forcing nowcast file (NetCDF) input
nos.OFS.met.forecast.YYYYMMDD.tCCz.nc Surface forcing forecast file (NetCDF) input
nos.OFS.hflux.forecast.YYYYMMDD.tCCz.nc Surface flux forcing forecast file (NetCDF) input
nos.OFS.obc.YYYYMMDD.tCCz.nc Open boundary forcing file (NetCDF) input
nos.OFS.clim.YYYYMMDD.tCCz.nc Climate nudging file from global RTOFS input
nos.OFS.river.YYYYMMDD.tCCz.nc River forcing file (NetCF) input
nos.OFS.init.nowcast.YYYYMMDD.tCCz.nc Initial condition file (NetCDF) input
nos.OFS.roms.tides.YYYYMMDD.tCCz.nc Tidal forcing file (NetCDF) input
nos.OFS.nowcast.YYYYMMDD.tCCz.in Runtime input file for nowcast (text) input
nos.OFS.forecast.YYYYMMDD.tCCz.in Runtime input file for forecast (text) input
nos.OFS.fields.nowcast.YYYYMMDD.tCCz.nc 3D field nowcast file (NetCDF) output
nos.OFS.fields.forecast.YYYYMMDD.tCCz.nc 3D field forecast file (NetCDF) output

If you append the model run name onto the path you will get:

Special Case - Great Lakes

The GLOFS data, the Great Lakes, is not structured in the same way as the data is for the other OFS models. GLOFS is composed of the nowcasts and forecasts for the lakes Huron (lhofs), Michigan (lmofs), Ontario (loofs) and Superior (lsofs).

Where lOFS is lhofs, lmofs, loofs or lsofs and BB is 00, 06, 12 or 18.

Contents of the NETCDF files.

Learn more about the Operational Forecast System models via the following link:

https://www.tidesandcurrents.noaa.gov/models.html