The difference between weather forecast and weather conditions

Weather forecast: calculate the weather situation according to the specific cloud image information; The weather is a phenomenon in the sky at present. The weather forecast faces a "chaotic" weather system full of "butterfly effect". That is to say, in the complex atmospheric movement, any slight disturbance may cause earth-shaking meteorological changes, and the error cannot be completely avoided, so it is almost impossible to make 100% accurate weather forecast.