@Dimitar-Mihaylov I do not ask you to do your own calculations with the raw data, just to imagine this [image: 1707860855253-3c376b26-39b4-4940-8660-89483c9a37ec.jpeg] This has been already asked to Windy…

@Dimitar-Mihaylov In fact the resolution of GFS is 0.25°. 1° being 111km, 0.25° is ~ 27 km. But this is when you consider the resolution in latitude. As far as I know when the NOAA presented this model they announced its resolution in longitude at Washington latitude. This sketch explains how you find 22 km. [image: 1702747417358-e7b1cecb-03e3-43c5-a3ee-ef933cef5ba7.jpeg] So now most model resolutions are displayed in longitude. The model IFS of the ECMWF which is the one shown in Windy has a 0.1° resolution. With the same calculation in longitude it gives 9km. Note most of the weather apps using this model of the ECMWF show in fact a free version called “WMO essentials” with a downgraded resolution of 0.5° or 43km. The fees for the 0.1° version that you get in Windy is very expensive.