The megaflood in the Jing-Jin-Ji region of China at the end of July 2023, driven by two typhoons and orographic precipitation, was a major disaster. In this study we show that the extreme rainfall event is well reproduced using the 3.25 km and 800 m Regionally Refined Mesh (RRM) configuration of the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM). A projected 5.8\%/degC increase in Jing-Jin-Ji precipitation under 2.16 degC warming by 2050 for this event is related to markedly increases in condensation rate and vertical velocity. Free-running simulations further show that the response of the mesoscale circulation to warming results in more pronounced local precipitation changes and shifts in rainfall patterns. The value of SCREAM for assessing the impact of climate change on extreme events and the importance of high-resolution climate modeling are emphasized.