@ivo
I don't understand what you are saying. Can you explain a bit more ? If I use IFS as model, fog is still substituted from ICON ?
Do you also know what parameters are required to display the fog pictogram ? There should be kind of tree : for instance minimum 92% of humidity at 2m, if no = no fog, if yes then the wind speed should be for instance less than 10km/k. If no, no fog, if yes, then we should check the next parameter.
Knowing what the parameters are and knowing the minimum value to be reached for each parameter will be very useful to understand when fog is displayed or not by Windy