Why is the weather forecast inaccurate?

The reasons why the weather forecast is not accurate are: human understanding of the mechanism of atmospheric motion is still very limited, the meteorological observation network can not be "sparse but not leaking", and the numerical weather forecast model can not fully simulate the evolution of the atmosphere.

1, human understanding of the mechanism of atmospheric motion is still limited. All kinds of weather are caused by the constant movement of the atmosphere. Due to the complexity of atmospheric motion, although with the development of science and technology and the continuous improvement of atmospheric detection means, human beings have deepened their understanding of the objective laws of atmospheric motion, but scientists can not really describe the fine structure of atmospheric motion.

2. Meteorological observation network cannot be "sparse but not leaking". Although meteorological observation has developed into a three-dimensional observation system covering the ground, air and space, ground observation stations, high-altitude observation stations, automatic weather stations, radar observation stations and meteorological stars have formed an observation network to monitor atmospheric movements and changes at all times.

But this net will miss small and medium-scale weather systems, just like catching small fish in a big net, it is easy to miss. Moreover, there may be errors in the observation data. For example, the observation results of wind direction and speed are all 2 minutes average, and there may be errors.

3. The numerical weather forecast model can't fully simulate the atmospheric evolution. The change of weather is the result of the change of atmospheric motion around the earth, which should conform to some laws of fluid mechanics and thermodynamics in physics. These laws can be written into mathematical equations in mathematical language.

People use high-performance computers to turn the problem of weather forecast into the problem of understanding mathematical equations. This method is called numerical weather forecast, which is the core of modern weather forecast. However, at present, any set of models can not truly simulate the evolution of the atmosphere, but only approximate, and there must be errors.

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1, empirical extrapolation method: also known as trend method, it is to infer the future position and intensity of various weather systems according to their past moving paths and intensity change trends on the weather map. This method is effective when the movement and intensity of the weather system do not suddenly change, or when the weather system does not regenerate or die. However, when it suddenly changes or the weather system is alive or dead, the forecast is often not realistic.

2. Similar situation method: also known as pattern method, it is to find some similar weather situations from a large number of historical weather maps and summarize them into certain patterns. If the current weather situation is similar to that before a certain model, it can be predicted with reference to the later evolution of the model. Because similarity is always relative and can't be exactly the same, this method often leads to errors.

3. Statistical data method: also known as correlation method, it is to use historical data to make statistics on the occurrence, development and movement of various weather systems in different seasons in history, get their average moving speed, and look for forecast indicators (such as cyclone generation and typhoon steering indicators). ) and make predictions. This method cannot be applied to examples that have never appeared in history or examples that are fast and slow.