No, its not the best. Also remember that prob 30 doesn't mean that there is a 30% probability! its a bit more binary than that. Prob 40 means that it is likely to happen, something like a 75% chance (ish) and prob 30 means it is not likely to happen, something less than 25% chance (ish). There is never a prob 50, 60 etc. Strange system isn't it and a can't imagine what sort of mind came up with it but strangely it actually works quite well.
You may have known that already in which case I am sorry for teaching my grandmother to suck eggs.
I always go with the TAFs on the day.