Why is the weather forecast for half a month checked yesterday different from the temperature checked today?

1. butterfly effect 1960 Lorenz, a professor at the Massachusetts Institute of Technology in the United States, used a simplified model to simulate the evolution of weather on the computer when studying the problem of "long-term weather forecast". His original intention was to improve the accuracy of weather forecast by using the high-speed operation of computer. However, contrary to expectations, many calculations show that very small differences in initial conditions will lead to huge differences in calculation results. Lorenz used an image metaphor to express his discovery: a small butterfly flapping its wings over Brazil may trigger a storm in Texas a month later-this is the famous "butterfly effect" in chaos, so it is impossible to achieve the accuracy of 100%, and there will be unexpected small fluctuations at any time. 2. Numerical Weather Forecast Most weather forecasts nowadays are no longer "looking at the weather from the clouds", but backed by powerful computers and complex mathematical models. Numerical weather forecast approximately represents the evolution law of the atmosphere as a set of mathematical equations. According to the initial state of the current atmosphere obtained by limited observation, the forecast of future weather or climate conditions can be obtained by solving the solutions of this set of equations. This is not the equation we learned in math class. The complexity of this equation requires a supercomputer that runs hundreds of billions of times per second to get an approximate solution. Have you found that the word "approximate" appears twice, which means that the equation and the final solution are not perfect, so sometimes there will be some errors in the final result, which is inevitable! 3. Did the children find that our current weather forecast is very accurate in predicting the impact of large-scale weather such as typhoons and cold air heading south, all because of meteorological satellites in the sky. The satellite cloud pictures sent back by meteorological satellites every day help us to predict the trend of large-scale weather, but the observation range of meteorological satellites is at least as large as that of a province, and it is responsible for observing the weather in the whole country. It is impossible to keep an eye on a city all the time, so satellites can't do anything about sudden extreme weather in a small area, such as thunderstorms, hail and tornadoes-which is also an important reason why these sudden extreme weather in a small area is difficult to predict.