Study on the formation and evolution of “6.3”damage wind

A damage wind event occurred on 3 June 2009 over an extensive area, which cause great damage and casualty at Shangqiu and North of Anhui and Jiangsu province that claimed 56 lives. The convective storm develop from superscell to bow echo squall line, Severe convection last more than seven hours. It's hard to forecast the storm's evolution and the surface damage wind. We studied these problems by analysis the mesocale environment , the storm's structure and the interaction between storm and circumstances, we get the following results:1) The mesoscale circumstances are favorable for Derecho where shangqiu damage wind occurred .2) Shangqiu wind storm is triggered by gust front of old thunderstorm clusters, when it move to the place where there is enough moisture. Storm developed into supercell storm with strong middle altitude radial velocity quickly. The surface wind damage was driven by downdrafts incorporation of multi-supercell; 3)The reasons of strong long-life squall line are :a)self-organization structure of squall line, b)interaction between squall line and surrounding inflow Jet, c)incorporation of line-shape cumulus which was triggered by dryline and overlapped disturbances again and again ; 4)The damage winds of bow echo are driven by Strong downdraft divergence flow , strong cold pool outflow and evaporation of stratus hydrometeors, estimate from radial velocity we can see that the effect of these three elements is almost equal. Incorporation of cold pool play an important role on Yongcheng damage wind.