When you pass time at the maximum zoomed out level, all cloud cover gets shoved into the top left of the map. Eg: Start action phase one level zoomed in, all is fine. Zoom out to max while paused, then back in, and pass time, all is fine.
Zoom out to max, pass time, then weather is FUBAR for the rest of the day. All cloud cover will generate in the upper left ~quarter of the map (Scotland), and disperse ~Newcastle or slightly farther South.
I have a few screens of it here. Starting out at 1 level zoomed in, then one zoomed out after passing time at that zoom level. That rough area is where all cloud cover appears and disperses for the rest of the day. (zooming back in does not fix it)
Also, the amount of clouds remains true to the weather report, just the entire maps worth gets thrown into and generated in that small area. Eg: If cloud cover starts @ 35%, as in the pics, it is quite dense. If it is 2% however, it is very thin, but only up there, you can actually see the patches warp when you advance time the first time.
For what it's worth, the area the clouds are restricted to, is roughly what the view area would be at one level zoomed in, if the window size were the same as maxed out. (If at one level in all the Propoganda posters and what not off to the right remained on screen.)
This only occurs in BOB, not BTR. Coincidentally BTR doesn't have that same reduced view area on max zoom out either.
Before:
