As I understand it, most, maybe all of the various internet
wx sites that provide grib presentations are simply passing on the outputs from one or more global wx models. This is raw data, straight from the computer.
The Australian BOM "Met Eye" service takes the various models and then has them interpreted by a real live human Meteorologist, one who knows about fronts (not included in the raw model output), local geographical effects and diurnal land/sea breeze issues... all things ignored by the global models, and which definitely influence the conditions in coastal cruising... a lot!
The Met Eye forecasts go out 7 days. Obviously, the further out you look, the less accurate the f/c will be. They update them fairly often, but I'm not sure about the actual timing of the updates... perhaps varies from day to day, according to conditions.
As I said earlier, we've had some experience with them in NSW and Tasmania, and have found them surprisingly good. Not perfect, but expecting perfection in a chaotic world is optimistic! I imagine that they are equally good in Queensland
, but don't have personal data to share.