Chengdu will have rainfall for 36 days in the next 40 days? You may not even check the weather forecast...

Yesterday

Topic #Chengdu will have rainfall for 36 days in the next 40 days#

Hot search

Netizens expressed their feelings

Chengdu can be renamed Rain City↓↓↓

today

Chengdu Weather

Once again on the hot search

Topic #Chengdu weather needs an official explanation#

Once again sparked a lot of discussion

Chengdu Meteorological Observatory responded

Generally, the weather station will only forecast the weather within a week.

Chengdu will have rainfall for 36 days in the next 40 days

Very inaccurate

Screenshot of China Weather Network Weibo

Although the average annual

Chengdu has about 15.1 days of rain in June

It's really rainy.

The latest situation found by the editor (for reference only)

Chengdu will have rainfall on 27 days in the next 40 days↓↓↓

Can the 40-day weather forecast be reliable?

What reference value does it have for us?

How is the mysterious weather forecast “measured”?

Is the 40-day weather forecast reliable?

The longer the weather forecast is, the lower the accuracy is. Since there is no subjective correction by the forecaster, the medium- and long-term forecast cannot accurately tell you whether the temperature will drop by 5℃ or 7℃ in ten days, nor can it accurately tell you whether it will rain 25 days or 20 days this month.

Before the introduction of medium- and long-term forecasts, meteorological departments usually only issued 3-7-day weather forecasts. However, as people's quality of life improves, the demand for meteorological information is also increasing, and 3- or 7-day forecasts can no longer meet the demand. Therefore, meteorological departments will use numerical models to predict medium- and long-term forecasts of 8-15 days or even 40 days.

Numerical weather forecasting is a science that uses high-performance computers to calculate future weather. Because atmospheric motion always follows certain physical laws, people write the laws of atmospheric motion changes into a series of mathematical equations, and then use high-performance computers to calculate and obtain future weather development and changes.

What is the reference value of medium and long-term weather forecasts?

Zhou Hui, national chief forecaster at the Hunan Provincial Meteorological Observatory, said that currently 40-day weather forecasts are generally given by numerical model forecasts. The forecast accuracy for the first 10 days can reach about 80%. However, the forecast deviation will increase with time in the later period, and coupled with the ever-changing weather phenomena, the uncertainty of model forecasts in the later period is relatively large.

Despite the uncertainty, medium- and long-term forecasts can already predict clear weather trends for a period of time in the future, allowing us to predict weather conditions longer in advance, such as whether it will rain, whether there will be continuous high temperatures or whether there will be cold waves, so that we have more time to prepare for response, and therefore have a high reference value.

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The weather situation is changing all the time, and the values ​​are also changing at any time. The medium- and long-term forecast will also adjust and revise the forecast results according to the changing values. The closer it is, the higher the accuracy. It is recommended that friends who have long-term travel or activity plans can pay more attention to refreshing the medium- and long-term forecast as time approaches to obtain more accurate forecast conclusions.

How is the weather forecast measured?

There are two key points in “measuring” the weather. One is to use numerical models to calculate on a supercomputer, and the other is for forecasters to make manual corrections.

Guan Chenggong, senior engineer at the Numerical Forecast Center of the China Meteorological Administration, said that supercomputers play a vital role in the two key links of weather forecasting: the collection and analysis of observation data, and numerical weather forecasting.

First, atmospheric observation data comes from ground-based and air-based observations.

Ground-based observations mainly include observations of temperature, air pressure, humidity, wind, etc. conducted by conventional meteorological observation stations, as well as the use of radar to obtain radar echo information.

Space-based observations mainly use polar-orbiting satellites and geostationary satellites to obtain satellite radiance information.

To organize the complex observation data into an orderly manner, combine it with conventional data, and adjust it to the atmospheric state that is closest to the actual situation, all requires strong support from supercomputers.

Secondly, after obtaining the Earth's atmospheric observation data, the meteorological department will calculate the values ​​of weather elements at equally spaced time points in the future based on the current state of the atmosphere and the surrounding environment, thereby obtaining future weather conditions.

On the other hand, manual corrections by weather forecasters are also very important. Numerical weather forecasts cannot fully simulate extremely complex atmospheric changes, and the forecasts made will inevitably be biased. Weather forecasters rely on their experience in using numerical models and combine them with local weather forecasting experience to make more accurate forecasts.

At the same time, Lan Yu, deputy director of the Severe Weather Forecast Center of the Central Meteorological Observatory, also said that the accurate forecast of disastrous severe convective weather is a huge challenge currently facing the meteorological field around the world.

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In recent decades, with the establishment of comprehensive observation systems such as satellites, radars, aircraft, and ground observations, as well as the continuous improvement of atmospheric science theories, the accuracy of numerical weather forecasts has been greatly improved.

In 2018, the accuracy of the national 24-hour rain and shine forecast reached 87%, the advance warning of severe convection reached 38 minutes, and the typhoon path forecast level continued to lead the world. Fu Guerlain, a senior engineer at the Central Meteorological Observatory, said that with the continuous advancement of forecasting technology, the accuracy and timeliness of forecasts are constantly improving. Basically, the area and intensity of heavy rainfall can be accurately predicted about 3 days in advance. At present, the accuracy of my country's 24-hour rainstorm warning can reach 89%.

But even though numerical forecasting has developed to a certain level, weather forecasting is also a predictive science. It is almost impossible to be 100% accurate in the foreseeable future, and there will always be errors in the forecast.

Scientific weather forecast

Spend the summer leisurely

Follow the rolling forecast

Reasonable travel arrangements

Source: Science and Technology Daily

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