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During 26–27 June 2022, mainly influenced by three mesoscale vortices, central‐eastern China (particularly for Henan and Shandong) experiences the first widespread torrential rainfall event of the 2022 flood season (maximum 24‐hr accumulated precipitation is ∼380.9 mm), resulting in severe social impacts. The three mesoscale vortices form and sustain under favorable background conditions, mainly including a strong upper‐level divergence, an intense middle‐level warm advection, and a powerful lower‐level convergence associated with a low‐level jet. Among the vortices, the vortex which forms over Shandong, lasts for ∼9 hr, and makes a much larger contribution than the other vortices to the accumulated precipitation, is defined as the primary vortex. More than a half of the hourly precipitation peaks in this event appear in the life span of the primary vortex, which is closely related to the variations of the vortex in its cyclonic‐vorticity and vertical extent. Backward trajectory analysis indicates that air particles originating from the lower troposphere southwest of the primary vortex contribute the most to its formation (∼82.7%). These air particles mainly experience a notable increase in their cyclonic‐vorticity due to convergence‐related vertical stretching, which directly renders the formation of primary vortex. During the whole life span of the primary vortex, convergence‐related vertical stretching is the most favorable factor for its development/sustainment, and the convection‐related vertical transport of cyclonic vorticity ranks second; whereas, the horizontal transport is the most detrimental factor. Moisture budget shows that Southeast China is the most important moisture source for this event (accounting for ∼48.9%). Plain Language Summary: Due to global warming, extreme weather and climate events occur with a higher frequency and a stronger intensity in China. Of these, a widespread heavy rainfall occurs in central‐eastern China during 26–27 June 2022, which causes severe impacts on society. Our attention is drawn to understand how the extreme rainstorm forms and where the main moisture sources are located. For this, we analyze this event by using automatic station data and reanalysis data and discover that three mesoscale vortices are the primary reason for the heavy rainfall. Among the vortices, the one with the longest life span contributes the most to the accumulated precipitation. The strong convergence in the lower troposphere dominates the formation/maintenance of the vortex. Southeast China continuously supplies moisture for the rainfall (∼48.9% in contribution). This research is helpful to enhance the understanding of this type of heavy rainfall event. Key Points: Affected by three mesoscale vortices, central‐eastern China experiences torrential rainfall, with a rainfall peak of ∼380.9 mm observedThe primary vortex, which is produced by vertical stretching, is directly related to more than a half of the hourly rainfall peaksSoutheast China provides ∼48.9% of the moisture for the rainfall, which is mainly transported by the Southwesterly/southerly wind [ABSTRACT FROM AUTHOR]

Explosive extratropical cyclone (EEC) is the main disastrous weather system over the ocean and offshore areas in the cold season. As a type of vertically deep system, after decades of studies, key features of EECs' vertical extents still remain vague. Based on a reasonably simulated entire‐troposphere‐thick EEC, this study analyzes variation of the EEC's vertical extent and investigates governing mechanisms for its vertical extending. Main findings are as follows: (a) the EEC's vertical extent showed consistent variation features with its central sea level pressure and lower‐level vorticity (correlation coefficients were ~0.9), whereas its relationship with EEC's maximum surface wind was not significant; (b) EEC's upward extending featured strong ascending motion and rapid cyclonic‐vorticity enhancement at the top level of the cyclone and obvious inflow (convergence) in the lower troposphere. (c) vorticity budget at the EEC's top level shows that net import transport of cyclonic vorticity (by westerly and northwesterly winds) from the trough west of the cyclone dominated its upward extending, and upward transport of cyclonic vorticity from levels below the cyclone's top level acted as the second dominant factor. In contrast, divergence‐related vertical shrinking around the EEC's top level was the most detrimental factor for the cyclone's upward extending. [ABSTRACT FROM AUTHOR]

A rarely seen entire‐troposphere‐thick (ETT) extratropical cyclone that induced a record‐breaking catastrophic rainstorm in Beijing (the largest since 1963) on 20 July 2016 was reproduced reasonably by a convection‐permitting Weather Research and Forecasting Model. This cyclone was the result of a vertical coupling of a lower, a middle, and an upper tropospheric cyclone, which formed at different times and locations. Dry air descending from the stratosphere through a tropopause folding process capped moist air to the middle and lower troposphere, making convection associated with the cyclone relatively shallow. Overall, cyclonic vorticity associated with the ETT cyclone enhanced much rapider than its wind kinetic energy (KE), and formation mechanisms of the ETT cyclone were characterized by layer‐wise features: (i) The formation of the middle and upper tropospheric cyclones was dominated by cyclonic vorticity transport, instead of cyclonic vorticity production, whereas the lower tropospheric cyclone was generated through both cyclonic vorticity transport and convergence‐related cyclonic vorticity production. (ii) Consistent with the cyclonic vorticity intensification, the formation of the lower and middle tropospheric cyclones featured an enhancement of rotational wind KE (in western section of the cyclone, this was mainly due to the work done by the pressure gradient force, but in eastern section, it was mainly due to the inward transport of wind KE by rotational wind), whereas the formation of the upper tropospheric cyclone featured a decrease in the rotational wind KE (particularly in its eastern section), which was in contrast to its increasing cyclonic vorticity. The export of wind KE by a southwesterly wind within the eastern section of the cyclone governed the rotational wind attenuation. Key Points: An entire‐troposphere‐thick extratropical cyclone that induced the largest rainstorm in Beijing since 1963 was reproduced reasonably by WRFInward transport of cyclonic vorticity was a dominant factor for the formation of the lower, middle, and upper tropospheric cyclonesWork done by pressure gradient force governed enhancement of rotational wind kinetic energy of the lower and middle tropospheric cyclone [ABSTRACT FROM AUTHOR]

Dabie vortices (DBVs) are a type of heavy-rainfall-producing mesoscale vortices that appear with a high frequency around the Dabie Mountain over the Yangtze River Basin. For a long time, scholars have found that DBVs tend to form when a low-level jet (LLJ) appears in their neighboring regions. However, the underlying mechanisms of this phenomenon still remain vague. This study furthers the understanding of this type of event by conducting detailed analyses on a long-lived eastward-moving DBV that caused a severe flood in the 2020 summer. It is found that the LLJ in this event was belonged to a nocturnal LLJ type, with its maximum/minimum appeared around 2100/0600 UTC. The diurnal cycle of LLJ affected precipitation and intensity of the DBV notably: As the LLJ intensified, vortex's precipitation and intensity both enhanced, and vice versa. The LLJ exerted two effects on the DBV's formation that are opposite to each other. The more important effect is that the LLJ caused intense lower-level convergence around its northern terminus. This convergence directly produced cyclonic vorticity through vertical stretching, which dominates the DBV's formation and enhances the convection-related upward cyclonic vorticity transport that acted as another favorable factor. The less important effect is that (i) the LLJ induced import of anticyclonic vorticity into the vortex's central region, which decelerated the DBV's formation; and (ii) the LLJ-related to strong ascending motions tilted horizontal vorticity into negative vertical vorticity, which reduced the growth rate of cyclonic vorticity. [ABSTRACT FROM AUTHOR]

On the basis of a 14‐year statistical dataset of the southwest vortex (SWV), 10 long‐lived and heavy rain–producing SWVs are selected for a series of convection‐permitting composite semi‐idealized simulations. After confirming the simulation has reproduced the common salient features of these selected vortices, the general underlying mechanisms for the formation of this type of SWV are investigated. Results show that the SWV formation is characterized by significant unevenness, as the fundamental characteristics and dominant factors for the cyclonic‐vorticity production vary from place to place. Overall, the eastern/western section of SWV mainly features favorable/unfavorable conditions for the cyclonic‐vorticity enhancement. The vorticity budget indicates the convergence‐related horizontal shrinking and convection‐related tilting contribute to the cyclonic‐vorticity enhancement in the SWV's eastern section, whereas in the western section, the terrain‐related tilting and horizontal transport result in the cyclonic‐vorticity reduction. [ABSTRACT FROM AUTHOR]