The NCEP/FNMOC Combined Wave Ensembles (NFCENS) product consists of a combination of wave ensemble outputs from the NOAA WAVEWATCH III wave ensemble system, and from the wave ensembles run by the US Navy Fleet Numerical Meteorology and Ocenographic Center (FNMOC). The product combines outputs from a total of 41 wave ensemble members: one control run and 20 members from the NCEP system, and 20 additional members from FNMOC.

The NCEP wave ensemble system has 20 members forced with bias-corrected GEFS winds, and one one control run, forced with deterministic GFS winds. These run on a global spherical grid with 1 x 1 spatial resolution, extending from 78S to 78N. The system runs four cycles per day (00, 06, 12 and 18Z), with forecast horizon of 10 days. The FNMOC wave ensembles has 20 members forced with their NOGAPS Ensemble Forecast System. The wave ensemble members run on grids identical to those used at NCEP, which facilitates the combination of outputs. Wave models are initialized with outputs from the data assimilation system NCODA. FNMOC wave ensembles run twice daily at 00Z and 12Z.

The NFCENS Combined Wave Ensembles Product consists of 41 individual wave ensemble members outputs. At this stage only significant wave heights (Hs) are provided. The following statistics are made available, derived from the combined wave ensemble: mean, spread and 8 levels of probabilities of Hs exceeding 0.6m, 1m, 2m, 3m, 4m, 5.5m, 7m and 9m. The product is made available twice daily at 00Z and 12Z.