On June 19, Shanghai got into the first day of the plum rain season featured by heavy rainfall, accompanied by short-term heavy precipitation. Facing this test, Shanghai Municipal Meteorological Service (hereinafter referred to as the Service) prepared with "31631" heavy precipitation risk warning response mechanism (hereinafter referred to as "31631"mechanism) to safeguard the city's "lifeline".

In June this year, the Service and ShanghaiMunicipal Flood Control Command Office jointly issued a regulatory document to explicitly strengthen "31631" mechanism at all points in time to realize the high degree of forecasting and warning and emergency response coupled for the flood season.

How does the Service operate this mechanism in advance？

The rainfall information across Shanghai on June 19, 2024.

Source：Shanghai Meteorological Service Center

"3 days"- On June 16, the Service issued a reminder of the heavy precipitation process to the local government, and jointly with ShanghaiMunicipal Flood Control Department to carry out consultations to analyze the type, the approximate period of heavy precipitation weather that may occur in the next 3 days.

"1 day"- On June 17, the Service issued the "Important Meteorological Information Bulletin", analyzing in-depth the atmospheric circulation situation and precipitation characteristics in the pre-plum rain season, and comprehensively evaluating the possible triggering of disastrous weather such as thunderstorms and gusty winds, high temperature and high humidity, as well as the impacts on the operation of the city, and putting forward targeted preventive suggestions.

"6 hours"- At 16:40 on June 18, a strong convection pre-briefing was issued six hours in advance. The Service reminded that there would be short-term heavy precipitation and thunder and lightning from midnight to the next day, with cumulative rainfall amounting to more than 50 mm. After receiving the message, the local water department at the first time to prepare in advance for the pre-lowering of river levels and other work.

"3 hours"- At 22:10 on June 18, Shanghai Central Weather Station issued a blue rainstorm warning signal and a yellow thunder and lightning warning signal 3 hours in advance. The city's four-level response of flood and typhoon control was synchronized to release.

"1 hour"- at the critical moment of heavy rainfall, the Service enhanced the monitoring and forecasting early warning services, depending on the circumstances to start a 1-hour disaster warning mechanism, notifying areas where heavy precipitation will fall in the next hour, the hourly rainfall intensity extremes, etc., and provide timely tips on risky and hidden dangers.

The successful implementation of "31631"mechanism cannot be separated from the solid support at the technical level. The upgraded Shanghai's regional high-resolution numerical weather prediction (NWP) models provide strong support for accurate forecasting, while the trial operation of the 1-kilometer short-range NWP model realizes hour-by-hour high-frequency, high-resolution and high-accuracy rolling forecasts.

Meanwhile, the continuous improvement of artificial intelligence (AI) forecasting capability and the operation of the China's first major city phased array radar network help convective scanning without blind zones and storm tracking without omission, thus efficiently guaranteeing accurate and reliable warnings of imminent disasters.

By 16:00 on June 19, there are 13 streets and towns' cumulative rainfall of more than 50 mm in Shanghai, flood control work is in order and the city runs safe and secure.

Editor: JIANG Zhiqing