Forecast Model Charts

Our animated forecast charts provide a powerful overview of weather systems and swell fronts active in your area. The following article describes how to use this data

Forecast charts overview

Forecasts can be viewed for the UK and Ireland under the Forecast Chart tab on the main menu. When Bigsalty talks of forecasts, we mean the prediction of wind and wave occurrences over the next seven days. Forecast data presented is the raw output of the GFS and NWW3 forecast models and in many cases it is up to your knowledge of your local spot as to how you interpret the data. Bear in mind that under certain situations local affects can have a big impact on the forecasted conditions. For example, a reasonable swell may be forecast but a strong offshore wind could be flattening the sea state. Wind may also either be increased or decreased by local affects not picked up by the forecast model such as sea breezes, katabatic winds and venturi affects.

Forecast time ranges

With any forecast as the time increases away from the present the forecast becomes progressively inaccurate. As inaccuracies creep in to the generated data models they become more and more exaggerated. Therefore, as a rule of thumb, you should expect that the first 2-3 days of a forecast should be the most accurate according to the day’s time frames and details. As we move past that, the predictions become more of an indication of events than a strict guide. Further still, near the end of the forecast run, the model will be quite experimental. Therefore, when planning trips using the Beach Search tools, bear the above facts in mind and plan for trips no more than 2-3 days in advance.

Forecast models used by Bigsalty

GFS Atmospheric Model

The numerical model run by Bigsalty to forecast all atmospheric data is the GFS (Global Forecasting System) made available by the NOAA. This generates data sets of a 0.5 degree resolution covering the entire globe which is equivalent to having forecasted data at points in a grid over the globe with 55km spacing. Because we are primarily focused on UK/Ireland conditions we subset this data and can interpolate the variables to any given exact location in this region.

NWW3 Wave Model

The model used for Bigsalty’s Wave forecast is the NWW3 (NOAA’s Wave Watch model), which covers the majority of the world’s oceans. It’s considered to be one of the most sophisticated models of this time and is operationally used for commercial and military forecasting. The data used to compile the NWW3 model is fed every six hours by thousands of actual observations from satellites, buoys, ships, weather stations and aeroplanes. Further details of the merits and errors of the Nww3 model are viewable at the link below polar.ncep.noaa.gov/waves/

It generates a highly accurate forecast but this data is, and always has been, for offshore predictions and does not predict true nearshore conditions. This has some benefits and drawbacks for us windsurfers, surfers and kitesurfers. It provides a very powerful tool to determine the quality and characteristics of swell that generates waves at the shore. It is, however, up to you to predict how this data will affect waves at your local spot. If you are new to this then it’s important to have a handle on the effects of wave height, wave period and wave direction displayed in this forecast. See interpreting wave data.