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    incorrect weather forecast and sudden lower data as exist

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    • A Offline
      Aleks Valdes
      last edited by

      The voyage was planned in 26.08.2023 and according the weather was expected to be till 31.08. Vessel have limitation 0.8m for waves and 10m/s wind.

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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 Offline
                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 )).

                    idefix37I 1 Reply Last reply Reply Quote 0
                    • idefix37I Offline
                      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 Offline
                          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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