Actually a meteorologist isn't just massaging the data. Models often have know biases, eg under predicts rain when there is an offshore wind, or doesn't model c

Actually a meteorologist isn't just massaging the data. Models often have know biases, eg under predicts rain when there is an offshore wind, or doesn't model complex local topography and gets mixing wrong, etc. Forecasters use their local knowledge to tweak the forecast, and achieve significant accuracy gains. But people are expensive, so they are affordable for high impact cases, like aviation weather.