Advice (GFS)


WAVEWATCH III Environmental Modeling Center

4 times per day, from 3:30, 09:30, 15:30 and 21:30 UTC
Greenwich Mean Time:
12:00 UTC = 13:00 BST
0.2° x 0.2° for Mediterranean
1° x 1° for Rest of World
Significant wave heights
The significant wave height is a commonly used statistical measure for the wave height, and closely corresponds to what a trained observer would consider to be the mean wave height. Note that the highest wave height of an individual wave will be significantly larger. The peak period is not commonly presented. The wave field generally consists of a set of individual wave fields. The peak period identifies either the locally generated "wind sea" (in cases with strong local winds) or the dominant wave system ("swell") that is generated elsewhere. Note that the peak period field shows discontinuities. These discontinuities can loosely be interpreted as swell fronts, although in reality many swell systems overlap at most locations and times (see spectra below).
The NOAA WAVEWATCH III™ operational wave model suite consists of a set of five wave models, based on version 2.22 of WAVEWATCH III™. All models use the default settings of WAVEWATCH III™ unless specified differently.
  1. The global NWW3 model
  2. The regional Alaskan Waters (AKW) model
  3. The regional Western North Atlantic (WNA) model
  4. The regional North Atlantic Hurricane (NAH) model
  5. The regional Eastern North Pacific (ENP) model
  6. The regional North Pacific Hurricane (NPH) model
All regional models obtain hourly boundary data from the global model. All models are run on the 00z, 06z, 12z and 18z model cycles, and start with a 6h hindcast to assure continuity of swell. All models provides 126 hour forecasts, with the exception of the NAH model (72 hour forecast). No wave data assimilation is performed. All models are based on shallow water physics without mean currents. Additional model information is provided in the table and bullets below. The four time steps are the global step, propagation step for longest wave, refraction step and minimum source term step.
Numerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. Although the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer and computer simulation that it was feasible to do in real-time. Manipulating the huge datasets and performing the complex calculations necessary to do this on a resolution fine enough to make the results useful requires the use of some of the most powerful supercomputers in the world. A number of forecast models, both global and regional in scale, are run to help create forecasts for nations worldwide. Use of model ensemble forecasts helps to define the forecast uncertainty and extend weather forecasting farther into the future than would otherwise be possible.

Wikipedia, Numerical weather prediction, of Feb. 9, 2010, 20:50 UTC).
Last updated: Tu, 16 Jul, 16:04 BST
These charts are for guidance only, actually gusts and wave heights may be considerably higher than those shown.

wind symbols

West: 5(knots)West: 5 (knots)
South West: 10(knots)South West: 10 (knots)
South: 15(knots)South: 15 (knots)