Numerical Simulation and Mesoscale Analysis of a Heavy Rainstorm on May 15, 2013 in Guangdong

By applying WRF model, this study gives detailed diagnosis of a heavy rain that happened in Guangdong from May 15 to 17.The result shows: The WRF model can simulate the heavy rainstorm center, distributed and intensity tendency. The stable Two troughs and one ridge circulation was the background condition of this heavy rainstorm. An upper-level jet stream, a lower-level jet stream and a vertical secondary circulation driven by them were the main dynamical mechanism of this process. An ascending wet jet induced by the dry cold air and the warm water vapor transported by south china sea summer monsoon was the thermodynamic condition of this heavy rainstorm. The topographic blocking effect slows down the southeast jet movement, which is beneficial to the formation of the extreme rainfall upstream. The dry cold air from the mid- and upper-levels of the troposphere that invaded the lower level due to the secondary circulation interacted with the ascending warm wet air flow from low levels being conducive to the releasing and development of baraclinic instability and convective instability energy, which was the triggered Mechanism of this heavy rainstorm.