Why did Shanxi, a country with "nine droughts in ten years, experience a sudden rainstorm in October?"

  Experts interpret the continuous heavy rainfall process in Shanxi

  Since October, many places in Shanxi have suffered continuous heavy rainfall. Taiyuan, Yangquan, Linfen, Changzhi, Luliang, and Jinzhong all set historical records of accumulated rainfall in early October.

Heavy rains caused serious natural disasters such as landslides, road interruptions, flooding in villages, collapsed houses, and casualties.

  This rainfall process has large accumulated rainfall, long duration, strong short-term rainfall, and prominent extremes. For this reason, the Shanxi Meteorological Bureau initiated a four-level emergency response to major meteorological disasters (heavy rain).

Known as the "Nine Droughts in Ten Years", why did Shanxi suddenly encounter this torrential rain?

  How heavy is the rain

  Shanxi is located at the eastern end of the Loess Plateau. "Nine droughts in ten years" is the basic condition of the province.

However, from 23:00 on October 2 to 23:00 on 6th, Shanxi suffered continuous heavy rainfall.

  The Shanxi Meteorological Bureau reported that the average precipitation in Shanxi Province reached 119.5 mm from 20:00 on October 2 to 8:00 on the 7th, which was more than three times the average monthly rainfall in October.

In the province's 117 counties (cities, districts), 18 counties (cities, districts) have precipitation exceeding 200 mm, and 51 counties (cities, districts) have precipitation between 100-200 mm, and the maximum accumulated precipitation is 285.2 mm .

  The data provided by the Shanxi Meteorological Observatory showed that during this heavy precipitation, the daily precipitation of 59 national meteorological observatories in the province exceeded the historical extreme value of the same period since the establishment of the station, and the cumulative precipitation during the process of 63 national meteorological observatories exceeded the historical extreme of the same period. value.

  Wang Hongxia, chief forecaster of the Shanxi Meteorological Observatory, said that this round of precipitation weather process has the characteristics of large accumulated rainfall, long duration, and outstanding extremes. The precipitation in the early period of the process is accompanied by thunder and strong convection weather, and the temperature in the later period drops sharply and continues to fall, which has an impact. Large and wide range.

  Where did the rainstorm come from

  Wang Hongxia said that the atmospheric circulation was stable during the precipitation process, which made the precipitation time longer.

Specifically, the abnormally strong western Pacific subtropical high first stretched westward and moved northward and then stably maintained in the Huanghuai area. The low-value system of the westerly belt formed a stable circulation situation in Shanxi that was high in the east and low in the west, resulting in long-term precipitation in Shanxi. weather.

  Abundant water vapor conditions make the accumulated rainfall larger.

The southerly air current on the west side of the subtropical high and the low-level southwest jet stream continuously transport water vapor from the South China Sea and the Bay of Bengal northward through the southwest region to the central and southern parts of Shanxi, providing a sufficient source of water vapor for continuous precipitation in Shanxi.

  In addition, low-level uplift conditions have been maintained for a long time, leading to local extreme heavy rainfall.

Wang Hongxia said that under stable weather conditions, the low-level shear line convergence system was maintained for a long time and the precipitation echoes repeatedly passed through central Shanxi, superimposing the complex topography of Shanxi’s Luliang Mountain and Taihang Mountain on the increase of easterly airflow precipitation, resulting in central and eastern Shanxi Province. The appearance of extreme heavy precipitation in the northern part of Linfen.

  In response to this extremely heavy precipitation process, the meteorological departments at all levels in Shanxi Province cooperated with each other to provide forecast and early warning services.

According to statistics, from October 3 to 7, the Shanxi Early Warning Information Release System issued a total of 848 early warning messages, including 10 provincial-level early warnings, 116 municipal-level early-warnings, and 722 county-level early-warnings for emergency rescue and disaster relief and transfer of people. Bought precious time.

  What to pay attention to in the follow-up

  Meteorological experts said that the secondary disasters caused by the recent heavy rainfall are relatively large, mainly including mountain torrents, geological disasters and house collapses, and the disasters are relatively scattered.

There is a local danger in the river, and the pressure of flood prevention is relatively high.

  Affected by continuous heavy rainfall, landslides and surface subsidence occurred in some areas of Shanxi Jinzhong, Luliang, Linfen and other places.

Up to now, Shanxi has launched the provincial level III emergency response to geological disasters and the provincial level III emergency response of natural disaster relief, and allocated 50 million yuan in provincial disaster relief funds to do its best in flood prevention and relief work.

  According to the latest weather forecast of the Shanxi Meteorological Observatory, there will still be light rain or showers in some areas of southwestern Shanxi in the next two days, and the temperature will drop significantly.

Experts suggest that the risk of continuous rainfall is extremely high, and the occurrence of disasters has a lag effect. All localities need to continue to do a good job in flood prevention, geological disasters, and inspections of river embankments, reservoirs and dams, and prevent the adverse effects of heavy rainfall on disaster relief work. Impact, do a good job of sanitation and epidemic prevention in advance.

Comprehensive Xinhua News Agency, The Paper