Meiyu front

During mid-spring to mid-summer, the upper circulation is typically west-east and the front is mostly stationary.

Along this boundary, mesoscale convective complexes (MCCs) or mesoscale convective systems (MCSs) tend to form and propagate eastward, giving a series of heavy downpours.

[1] The system extracts moisture from the South China Sea and sometimes the Bay of Bengal.

The low-level warm air is lifted by the low level jet on the equator side of the baroclinic zone.

The deep vertical motion giving birth to organized MCCs/MCSs is especially strong when the low-level warm air enters the area situated beneath the jet entrance region aloft.