Forecasts Broadcast under the GMDSS

Amended, January 2021

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Weather forecast services broadcast under the Global Maritime Distress and Safety System (GMDSS).

The GMDSS

When these pages were first written, the GMDSS was the prime source of all Marine Safety Information (MSI) including weather forecasts and warnings. It is still a vital service and sailors should know what is available, when and how to get it. However, much MSI, especially weather MSI, is now readily available on the internet along with much other weather information of more general use than “official” weather broadcasts. Although GMDSS communications are as reliable as any other current system, it is not operationally robust in that URLs and page content can change without warning even those of vital safety information. It is only sensible to maintain skills and equipment to enable reception of MSI over GMDSS channels even though this might entail coastal sailors having NAVTEX and HF/MF/SSB radios in working order and used from time to time. At some stage, safety of vessel and crew may depend on the GMDSS. Likewise, long distance sailors should still carry HF/MF/SSB transceivers even though they may be using Inmarsat or Iridium to obtain GMDSS information.

The value of the GMDSS and the necessity to be able to use it cannot be overstressed. Forecasts and warnings are necessarily very broad brush but they do have the inestimable value of human, intelligent input. Experienced forecasters can give the best interpretation of the guidance from Numerical Weather Prediction models. They can see the output from models run by other Met services and from their own computer run under slightly varying initial conditions (known as ensembles). The best use of forecasts is to study both GMDSS text forecasts and other data such as GRIB files and synoptic charts.


These pages are about GMDSS services for Europe, the eastern North Atlantic, the Baltic and Mediterranean. Depending on the area and forecast type these broadcasts may be by VHF, NAVTEX, Inmarsat or Iridium and HF/SSB radio.



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