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    How to read Meteogram

    Frequently Asked Questions
    meteogram
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    • F
      fhamilton36 last edited by

      That's great. What if I want to plan sailing from the Chesapeake to the Grenadines, a few months in advance. Is there historical data?

      idefix37 1 Reply Last reply Reply Quote 0
      • idefix37
        idefix37 Sailor Moderator @fhamilton36 last edited by idefix37

        @fhamilton36
        No Windy does not provide historical data.
        Better to use the Pilot Charts than verifying days after days what was the weather during the last 10 or 20 years:
        https://community.windy.com/topic/9788/historical-wind-data?_=1619461576536

        D 1 Reply Last reply Reply Quote 2
        • D
          dorucalinciobanu @idefix37 last edited by dorucalinciobanu

          Hello!
          If there is rain in the Meteogram at 4AM, does it mean it will rain from 1AM to 4AM, from 2:30AM to 5:30AM or from 4AM to 7AM? Thank You!

          1 Reply Last reply Reply Quote 1
          • vsinceac
            vsinceac | Premium last edited by vsinceac

            fc644c48-fb4a-4326-a2b3-9226839e0434-image.png

            ¯\_(ツ)_/¯

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            • D
              dorucalinciobanu @vsinceac last edited by

              @vsinceac Thank You!

              1 Reply Last reply Reply Quote 1
              • G
                GreatKingnan last edited by GreatKingnan

                Hi, I've just found that the values of the 'last 3 hours' precipitation are different in the Meteogram and the layer data. For example, in this picture (https://imgur.com/k0uKcEq), the value derived from the weather picker is 71mm, but the value from the basic Meteogram on the same point is 92mm, which one is correct? Is it resulted from the different definition of the two rainfall value?

                Another question is, the value of 'Rain' in Meteogram is 78mm, and the convective rainfall is 14mm. And the sum of them is equal to the value in the basic meteogram, 92mm. So the 'blue Rain' term is actually the 'large-scaled precipitation?' and the value 92mm is the total precipitation, the sum of large-scaled and convective precipitation, right?

                Thank you!

                123

                Korina 1 Reply Last reply Reply Quote 0
                • Korina
                  Korina Administrator @GreatKingnan last edited by

                  @greatkingnan Hello, the values are different since they are calculated differently. The Rain, Thunder layer shows accumulation in the last 3 hour.

                  Korina

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                  • G
                    GreatKingnan @Korina last edited by

                    @korina Thanks! So the value in Meteogram is the precipitation accumulated over a quite different time period compared to the Rain & Thunder layer? What's the time period you'd applied to do the calculation?

                    And I'd like to know whether the value of 'rain' in Meteogram & Airgram represents the large-scale precipitation or not? According to the description of parameter on ECMWF's website, total precipitation is the sum of large-scale & convective precipitation. It seems that the total amount of precipitation has been split into two parts in the bar graph in Meteogram: the large-scale term and convective term. Furthermore, the sum of 'Rain' and 'Covective' is exact the value in basic list, which might indicates the total precipitation. As a result, the term 'Rain' might be interpreted as the large-scale precipitation part in Meteogram.

                    Korina 1 Reply Last reply Reply Quote 0
                    • Korina
                      Korina Administrator @GreatKingnan last edited by

                      @greatkingnan Hello, the Rain, Thunder layers shows data for last 3 hours. The detailed forecast shows data calculated for 3hr or 1hr depending if you are Premium user or not. Therefore those values cannot be the same.

                      Korina

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                      • G
                        GreatKingnan @Korina last edited by

                        @korina Thanks for your help! Yes, I know exactly the data in Premium version and free version are different. But...Actually, I'm trying to figure out the differences between the rainfall values shown on the 'Rain & Thunder' layers and basic weather forecast on the same place. I just found they aren't exact the same value, especially for heavier rainfall cases, so I have no idea which one is correct. I guess it might be caused by the different definition of accumulated time period or the interpolation between each grid point.

                        Korina 1 Reply Last reply Reply Quote 0
                        • Korina
                          Korina Administrator @GreatKingnan last edited by

                          @greatkingnan Hello, detailed forecast or Rain, Thunder layer shows different data based on different calculations. Detailed forecast is more precise if you want to check the predicted amount of precipitation.

                          Korina

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                          • C
                            chobi-chan last edited by

                            Thanks, Korena for your very easy to understand description♪
                            Meteogram on Windy.com is my favourite weather forecast❤

                            1 Reply Last reply Reply Quote 0
                            • J
                              jev12b | Premium last edited by

                              What is the arrow on my location pointing towards? As I turn to face a different direction, the arrow swings to point toward something else. It's not making any sense to me; what is its purpose?

                              idefix37 1 Reply Last reply Reply Quote 0
                              • idefix37
                                idefix37 Sailor Moderator @jev12b last edited by idefix37

                                @jev12b

                                This arrow appears at your GPS position on the Radar layer and shows a fixed or inconsistent direction. It has no use.

                                63E2F732-9E42-459B-9A5B-DCC3223F4926.jpeg

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                                • F
                                  fran_j last edited by

                                  Hi,
                                  I wanted to know what criteria you use for the elaboration of the meteograms. this is the one from the ECMWF.

                                  https://confluence.ecmwf.int/display/FUG/Selection+of+grid+points+for+Meteograms

                                  Korina 1 Reply Last reply Reply Quote 0
                                  • Korina
                                    Korina Administrator @fran_j last edited by

                                    @fran_j Please have a look at https://community.windy.com/topic/10309/cloudbase-meteograms?_=1630065415375

                                    Korina

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                                    • N
                                      natural lamp last edited by

                                      Very good summary, very helpful to the net friend ~

                                      1 Reply Last reply Reply Quote 1
                                      • Mark Mansfield
                                        Mark Mansfield last edited by

                                        On the Meteogram, what does the letter 'K: at the cloud base mean ? I have it set to show it on feet, but soem shows for example 17K

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                                        • J
                                          jp_windy65535 @Mark Mansfield | Premium last edited by

                                          @mark-mansfield I think it means thousands (of feet) altitude.I think

                                          Mark Mansfield 1 Reply Last reply Reply Quote 1
                                          • Mark Mansfield
                                            Mark Mansfield @jp_windy65535 last edited by

                                            @jp_windy65535 thank you, that does make sense, but then why does some heights show as feet , for example 6900, and others as 15K for example?

                                            1 Reply Last reply Reply Quote 0
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