Abstract:Using MICAPS 3.1, the mesoscale automatic weather stations (AWS) and Doppler radar, the rainstorm in the southeastern Guangdong with the rainfall exceeding 600 mm within 13 hours on June 25, 2010 is analyzed. It is shown that the direct impact system of this extreme precipitation is the deep high altitude cold vortex which located south and moved slowly; the strong low level jet (LLJ) and LLJ provided sufficient moisture and dynamic conditions; and that the organized arrangement of the multi single storm activity, the ground quasi stationary front and the mesoscale warm shear line which maintained for a long time are the main causes for the formation of “train effect”. The precipitation echoes move along with the total surface center, and the special terrain is also one reason of the “train effect”. The reflectivity images have shown that the banded heavy precipitation echo can be a low mass center structure and then strong vertical development. The speed image with a “bull eye” structure shows that there was a low level southwest jet. Based on these studies, a “train effect” storm model is proposed.