Motivation: The moisture characteristics surrounding heavy-rain-producing, quasi-stationary MCSs along the synoptic-scale Mei-yu front are often extremely moist.

The sheer diversity in pre-storm environmental characteristics has received more attention in recent years. Since most conceptual models on MCS organization and maintenance are derived from observation/simulations on continental daytime MCSs. Does these models still hold in a drastically different environment?

What have we done: 
We designed and executed two weeks of intense observations (despite soft lock-down) on two Mei-yu MCS cases. High temporal resolution soundings were launched to document the pre- and post-storm environmental evolution. This small-scale experiment is to prepare for the international TAHOPE 2022 field campaign, which was planned to take place last year but postponed by 2 years due to the pandemic.

Interesting preliminary findings:

One of the more notable findings is the lack of defined cold air outflow emitted from the MCS. Radar-derived winds in the above figure show consistent southwesterly flow, with no signs of divergent flow anywhere. However, secondary cells were initiated at regular horizontal interval (CI1,CI2) to the southeast of the MCS. CI1 and CI2 can potentially be explained by the lifting of unstable air by trapped convectively-generated gravity waves. 

We currently plan to explore geographical diversity in convective organization by comparing observations gathered during a sister campaign by US partners (CSU etc.) focusing on MCSs in the US Great Plains.