What source of weather data Windy use?


  • Moderator

    .... now,
    if I go to satellite layer and activate pressure isolines (isobars)
    55c12f34-3800-498f-83a9-5ebafcc898e1-εικόνα.png
    I see those for Sat 16 May !!! with the 1021 hPa High over Morocco
    (although sat. image is for today 12 May).



  • As said in my previous post above, if forecasts and satellite image layers are displayed together on map, there would be a bug: they cannot be contemporary (excepted at full hours, maybe).

    Satellite images are provided every 10 or 15 minutes; Windy should obtain that worldwide mosaic by merging images from differrent satellites, taken at small time difference (a couple of minutes or so, but surely not hours).

    When combining satellite and atmospheric pressure layers together on map, then playing the animation over the whole available period on timebar (i.e. last 2, 6 or 12 hours), one can see that the pressure layer remains static over the whole period, while satellite images layer change at each time step...

    Thus the pressure isobars layer doesn't follow current value on timebar as expected, which is wrong from my pov.

    Having a static pressure isobars layer combined with animated satellite images would be useful for some specific deep analysis, but in such a case the validity time of the static layer should be clearly displayed on UI (I was not able to find it).


  • Sailor

    @Gkikas-LGPZ
    It was quite obvious for me that the isobars cannot match perfectly the satellite layer. And to get the best compromise it is necessary to set first the timeline on the current time. But I agree with you, that could be done automatically by Windy. From a theoretical point of view, it is wrong to mix forecast and observation. So in this case, Reported wind and Reported temperature should not been displayed at same time with all forecast layers. They show crazy values if the timeline is set 12 hours ahead and more... Windy needs a bit of understanding and training.


  • Moderator

    From a development point of view:

    • Should there be some type of pop up warning about mixing these combinations of layers together?

    • Or should it just be impossible to mix these combinations in the first place?

    What are everyone's thoughts about this?


  • Moderator

    @jmh2002
    My opinion:
    Satelitte layer must be "mixed" with isobars and/or other isolines
    ONLY if those isolines reffer to the time of sat. image (plus/minus 1 hour).
    I agree with idefix37 that theoretically is wrong to mix forecast and observations
    but practically I like to have sat. + isolines (isohypses) at 850 or 700 hPa
    to predict the direction of thunderstorms movement.



  • I think the best would be to clearly display on UI the validity time of the static data displayed on isolines layer (pressure, temperature, etc.).
    This way I think nobody would say that it is a bug: users should easily understand this.
    It is the same as when displaying a time series of observed data today AND of the data observed one year ago, on the same 2D plot; this is often used in analysis and it is really useful when the validity time of each time series is clearly labelled.


  • Sailor

    @jmh2002
    I don’t think a warning pop up would be a good idea (it is not in the Windy culture). IHMO it could be done automatically when isobars are selected together with satellite layer i.e. isobars should be displayed at about same hour as the last satellite observation as @Gkikas-LGPZ said.
    I think this is possible in the same way as when you select Rain accumulation with ECMWF at 10 days and switch to ICON, the time lapse is automatically set back to 12h.


  • Moderator

    @Korina @developers

    Please review these last comments and note and discuss with the development team regarding how this can be improved, thank you :)


  • Administrator

    @jmh2002 @idefix37 @vsinceac Hi all, it seems as a bug, I will let our development team know. Thank you for reports!



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