  Mesoscale convective systems (MCSs) are crucial components of the
hydrological cycle and often produce flash floods. Given their impact, it is
crucial to understand how they will change under a warming climate. This study
uses a satellite- and radar-based MCS tracking algorithm on
convection-permitting climate model simulations and examines changes in MCS
properties and precipitation structures between historical and future
simulations. An underestimation in MCS total precipitation is evident in
historical simulation compared to observations, due to model's depiction of MCS
precipitation area and summertime occurrence frequency. Under pseudo-global
warming, increases in MCS frequency and total warm season precipitation are
observed, most notably in the southern U.S. The precipitation intensity and
precipitating area generated by future MCSs also rises and results in an
increase in precipitation volume. MCS precipitation structures are further
classified into convective core and stratiform regions to understand how change
in these structures contributes to future rainfall changes. In a warmer
climate, the stratiform region demonstrates minimal change in size, but
increases in mean precipitation rate and mean maximum precipitation rate by 15%
and 29% are noted, respectively. A more robust future response is observed in
the convective core region, with its size, mean precipitation rate and mean
maximum precipitation rate increasing significantly by 24%, 37% and 42%,
respectively. Finally, by examining the environmental properties of MCS initial
condition, future intensification of convective rain may be attributed to a
combined effect of substantial increases in atmospheric instability and
moisture availability.
