Robin,
I am not arguing with you or anyone else. I need specific cases and I will have them investigated.
If you have a specific example of a forecast and actual being miles apart give me the ICAO code and time and date.
How far from accurate are you saying that the front timings are off?
I am not sure I understand your point about clouds on hills can you explain more? My understanding is that even on CAVOK days you are likely to get cloud on hills due to orthographic lifting and wave effect.