利用常规气象观测、多普勒雷达、卫星和区域自动站观测资料及NCEP再分析资料，对2011年6月11日豫北局地强对流天气的预报预警特征和触发机制进行分析。结果表明：局地强对流天气是在东北冷涡背景下产生的，高低层中尺度影响系统（槽、切变线和大风速轴）交汇处右侧为强对流发生潜势区。局地强对流天气发生前，CAPE较大，0-6km垂直风切变达到中等偏强，有利于超级单体的形成和发展。高空冷平流南侵、低层暖平流北上，有利于大气对流不稳定度进一步加大。中-β尺度强对流云团在东北冷涡槽底后部形成，其发展演变对局地强对流天气预报预警有参考意义。强对流回波经历了细胞状、带状发展期和块状减弱期。回波带南侧形成的超级单体造成了局地强风雹天气，冰雹发生时伴有“三体散射”现象。冷空气和地面辐合线是强对流天气的主要触发机制，其中地面辐合线还对强对流系统的组织形式具有重要作用。%Based on the conventionally meteorological observation data, Doppler radar data, satellite data, meteoro- logical data from regional automatic weather stations and the NCEP reanalysis data, the forewarning characteristic and trigger mechanism of a local strong hailstorm occurred on June 11,2011 in the northern He'nan province were analyzed. The results show that the local severe convective weather occurs under the background of the northeast cold vortex, and the potential area of severe convective weather is located on the fight side of the junction areas of upper and lower mesoscale synoptic system( trough, sheer line, the axis of larger wind speed). The CAPE values are large and the vertical wind sheer from 0 km to 6 krn determined from the revised sounding data before the local severe hailstorm weather happens is moderate or strong, which facilitate the formation and development of super- cell. The convective instability of atmosphere increases while the cold advection in upper level moves southward and the warm advection in lower level moves northward. The meso-fl-scale convective cloud cluster is generated in the rear of the northeast cold vortex and its development and evolution have some certain reference values for weather warning. Strong convective echo goes through the developing stage with cell shape to band shape and the weakening stage with block shape. The supercell generated on the south of the convective echo-belt results in the characteristic of 'three-body scattering' when the local severe hailstorm weather appears. The cold air and surface convergence lines are the important trigger mechanisms for severe convective weather, and the surface convergence lines are indicative for strong convection weather.
展开▼
