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    incorrect weather forecast and sudden lower data as exist

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    • A Offline
      Aleks Valdes
      last edited by

      windy 1 27.08.jpg

      In morning 27.08 the weather forecast showed other situation for our position.

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      • A Offline
        Aleks Valdes
        last edited by

        In evening updates 27.08 the weather become worse for our position and operation we doing.Windy  27.08.jpg

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        • A Offline
          Aleks Valdes
          last edited by

          But if you look at weather forecast from 25.08 it seems more precise.
          The question is why there is a couple of days announced in 26.08 looks good and suddenly not.windy 25.08.jpg

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          • A Offline
            Aleks Valdes
            last edited by

            28.08.jpg
            In reality 23kt wind 27kt in gust.
            Waves 1.2m

            idefix37I Yves70Y 2 Replies Last reply Reply Quote 0
            • idefix37I Online
              idefix37 Sailor Moderator @Aleks Valdes
              last edited by idefix37

              @Aleks-Valdes

              Weather forecasts are not exact calculations. There is a part of uncertainty in the weather prediction. In Windy, forecasts are provided directly by weather models.
              To have an evaluation of the uncertainty it is important to look at the forecasts of several models.
              For example in the next days on your voyage location :

              051E1269-B1A7-48AB-BD37-7095D9CAD4B5.jpeg

              Why can a model vary its forecast during the period of 4 days before the deadline? It repeats the calculations 4 times a day and there is little chance that the result will be perfectly constant over 4 days. Otherwise just one calculation per day would be far enough.

              In addition to Windy, at sea you must rely on official marine advisories. But they are never very precise as example:
              WIND: Northwest 3 to 5 Bft, backing west or southwest 3 or 4 Bft.
              SEA STATE: Slight, occasionally moderate.
              WEATHER: Showers.
              VISIBILITY: Good.
              For this reason, it's a bit strange that you plan to sail at this distance in Baltic Sea with a boat that cannot withstand more than 20 knots of wind and 0.8 m of wave height, even if we are in the summer season. Or, is it a special service and research vessel with only inshore and restricted capabilities ? ….To investigate on the Nord Stream pipeline sabotage location where you placed a favorite location ? :)

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              • Yves70Y Offline
                Yves70 Meteorologist @Aleks Valdes | Premium
                last edited by idefix37

                @Aleks-Valdes as said by @idefix37, to get a better forecast you should vary and compare the models. One of the problem here is that for each model you only get a single forecast. Nowedays, weather institutes use more and more weather model ensembles. For instance, ECMWF can calculate 21 single forecast by playing on several parameters so in place of getting a single forecast calculated from a lot observations, you will get a set of probabilities associated to a parameter you wish to know : rain, snow, wind speed,… When your time horizon is more than 4 days, model ensembles are very powerful

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                • A Offline
                  Aleks Valdes
                  last edited by

                  Thanks all for comments.
                  The problem actually that there is no service like on Dogger bank to have precise weather for vessels position. As survey vessel we belong to weather condition and it is complicated situation to decide when is time to hide in port. Yes, we cannot do 20 knots and if 1.5 waves catch vessel at sea everyone will be happy )).

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                  • idefix37I Online
                    idefix37 Sailor Moderator @Aleks Valdes
                    last edited by

                    @Aleks-Valdes
                    OK, I understand. It is difficult for you to decide when you can cast off mooring when the weather and sea conditions are close to the boat limits.
                    So for the wind forecast, look at the Compare table where there are several models for your area. And for waves try the 3 models available to confirm or not the prediction of the default model ECMWF.

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                    • M Offline
                      marçal mello | Premium
                      last edited by

                      Velocidade do vento invertida, vermelho dando baixa velocidade e azul muito vento !!!!! Velocidade errada em todos os pontos !!!!!
                      Rio de Janeiro e América do Sul toda !!!!!

                      idefix37I 1 Reply Last reply Reply Quote 0
                      • idefix37I Online
                        idefix37 Sailor Moderator @marçal mello
                        last edited by idefix37

                        @marçal-mello
                        You probably see this bug on Android device?
                        If so, this bug should be fixed in next release
                        https://community.windy.com/topic/28158/wind-gusts-not-working-well-at-all

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