The comparative analysis of two MCSs during a heavy rain event in northeast Hubei province

Based on GFS reanalysis, conventional observation, Doppler radars and wind profile's unconventional observations, the extreme precipitation occurred in northeast Hubei province on July 12-13^st 2012 is comprehensively analyzed focusing on the movement and structure of two successive MCSs and its development mechanism. The results show:① The two MCSs were under different dynamic mechanisms. MCS1 is mainly caused by the strengthening of local Meiyu front and the outburst of thunderstorm. MCS2 is characterized by the strong coupling of the low-level Meiyu front shear strong convergence and the high-level strong divergence.②On surface filed, MCS1 showed a stronger thunderstorm outburst, a deeper cold pool which spreading mainly along the direction of MCS1, and a more intense convection trigger.③ Structurally, when MCSs propagated forward, newborn, mature, and decaying cells lined along the echo long axis and sequentially arranged from downwind to upwind. When MCSs propagated backward, the opposite is true. In mature stage, the MCSs are backward propagated, moved slowly and were even in quasi-static state. Newborn cells line is much more close to the mature one, conducive to the maintenance of MCSs. In that case, the intensity of precipitation is maximized.