@idefix37 thx for the clarification. actualy i wasn't asking for more details. and i'm not expecting these. imho "removing" the colored overlay does make an sence to me either. for me (Berlin area, Germany) and in my screen the overlay is removed on a visible area of 40 by 25 km.

if i zoom into a map too much, the wind strength overlay just goes away and without it becomes pretty much useless for me (as a regatta sailor). why?