The GEFS Wave Model is the NCEP/EMC Global Ensemble Ocean Wave Forecast System. Due to uncertainty in the forcing wind fields, ocean wave models have a finite limit of predictability. The purpose of GEFS is to reliably extend long-range predictions by statistically accounting for the variations in the winds. This is done by unifying the GEFS wave model with the GFS wave model, but with 30 different wind fields, one initial wave field, and 30 separate runs to track the evolution of the wave environment. The wave model has a spatial resolution of 0.25 x 0.25 degrees. The system runs four cycles per day (00, 06, 12, and 18Z) and produces three-hourly forecasts out to 384 hrs (16 days). The GEFS results presented here are the mean of those 30 individual runs. As a result of this averaging, occassional abrupt jumps in wave period and direction can be expected.

NCEP (National Center for Environmental Prediction) is the part of the US National Weather Service responsible for running the myriads of numerical weather prediction models covering aviation weather, atmospheric forecasts, ocean wave forecasts and space weather, and disseminating the results. EMC is the Environmental Modeling Center. EMC is responsible for the development, improvement, and implementation of numerical prediction systems.

Warning - Forecasting wave heights within 1.5 foot (0.45 m) of the actual wave height, as recorded by a wave buoy, is typically excellent to very good out to 3 days, fair to middling from 3 - 7 days, poor from 7 - 10 days, and statistical noise for forecasts longer than 10 days. This holds for any and all wave models you may be looking at, no matter how fancy the presentation. We provide long-range forecasts with this in mind, Caveat Emptor. To confirm this, a comparison of GFS and WAM wave forecasts compared to NDBC wave buoy data can be reviewed at Wave Model Validation