Extended Abstract

MCVs are known to be important circulation features associated with heavyprecipitation features downstream of the Tibetan Plateau. Recent studiessuggest that MCVs can generate secondary convection (Fritsch et al. 1994) thatcan produce heavy rainfall and flooding over the Yangtze River valley and theHuaihe River Basin (e.g., Sun et al. 2010). The mechanisms occurring in UnitedStates extreme-rain events illustrated in Fig. 5 may be similar to those occurringover China. Moreover, the MCVs contributing to the heavy rainfall may be linkedto potential vorticity anomalies generated by upstream mountain barriers: theRocky Mountains in the United States and the Tibetan Plateau in China (Li andSmith 2010).5. Summary and conclusionsThis paper reviews synoptic and mesoscale mechanisms associated withextreme convective rainfall, with specific attention to the modes of organization ofconvective systems that are responsible for heavy precipitation. While synopticconditions that provide abundant moisture and instability are critical for settingthe stage for heavy rainfall, it is the existence of mesoscale processes – a liftingmechanism and favorable convective organization and cell propagation – that isnecessary for extreme rainfall to occur. A study of United States extreme-rainfall,flash-flooding convective episodes indicates that two-thirds are associated withmesoscale convective systems (MCSs). Three recurring patterns of mesoscaleorganization were found in such MCSs: trailing-line/adjoining stratiform, backbuilding,and trailing stratiform structures. Mesoscale convective vortices(MCVs) are also frequently implicated in extreme rainfall, where dynamical liftingon the downshear side of the vortices coupled with a low-level jet conspires togenerate intense, quasi-stationary convection.Acknowledgments. This research has been supported under NSF Grant Nos.ATM-0639461 and ATM-0966758, NASA Grant Nos. NNX07AD35G andNNX10AG81G, and NOAA Office of Global Programs Grant No.NA07OAR4310263. Much of the work reported herein involves the graduateresearch of Matt Parker and Russ Schumacher, to whom the author is greatlyindebted.ReferencesAsai, T., S. Ke, and Y. Kodama, 1998: Diurnal variability of cloudiness over EastAsia and the Western Pacific Ocean as revealed by GMS during the warmseason. J. Meteor. Soc. Japan, 76, 675‒684.Doswell, C. A., III, H. E. Brooks, and R. A. Maddox, 1996: Flash flood forecasting:An ingredients-based methodology. Wea. Forecasting, 11, 560–581.Fritsch, J. M., J. D. Murphy, and J. S. Kain, 1994: Warm core vortex amplificationover land. J. Atmos. Sci., 51, 1780–1807.Geng., B, and H. Yamada, 2007; Diurnal variations of the Meiyu/Baiu rain belt,SOLA, 3, 61-64.-8-