宁夏平罗一次雷雨大风、冰雹天气分析

Analysis of one thunderstorm and hail weather in Pingluo of Ningxia

利用常规气象资料、探空资料、卫星云图及银川天气雷达资料对2013年7月4日发生在宁夏平罗的雷雨大风和冰雹过程进行简要分析.结果表明,降雹前地面有弱冷空气的入侵,850 hPa为暖湿切变,700 hPa为干暖气团控制,500 hPa则为干冷空气;K指数、沙氏指数Si和θse都表明有较强的不稳定天气产生;降雹前700 hPa之上大气垂直速度为负值区,最大上升速度位于400 hPa附近,最大速度区位于-10^-30℃层,有利于冰雹对流的形成和发展;在多普勒雷达反射率因子图上出现"V"形缺口回波,最大反射率与垂直累积液态含水量中心最大值相对应,在雹云演变过程中,具有一定的临近预报指示意义.冰雹指数当持续出现"△"或"▲"报警时,极有可能产生强烈的对流天气.

Using conventional meteorological data, radiosonde data, satellite images and weather radar data, once thunderstorm and hail weather process were analyzed, which occurred in Ping Luo of Ning Xia in July 4, 2013. The results showed that there was a weak cold of ground intrude into the air before the hail happened, warm and wet shear pressure was at 850 hPa,dry air mass control pressure was at 700 hPa, dry cold air pressure was at 500 hPa; K index, Siindex and θseshow that strong unstable weather produced; Atmospheric vertical velocity was negative zone over 700 hPa before hail occurred, the maximum increase rate was nearly at 400 hPa, the maximum speed zone located between-10 and-30 ℃ layer, these conditions were conductive to formation and development for hail convection; 'V' notch echo appears on Doppler radar reflectivity factor graph,maximum reflectivity corresponded to water content maximum of vertical integrated liquid center; In the hail cloud evolution,there were some implications for nowcasting. When Hail Index alarm's symbol is '△'or'▲'persistently, it might produce strong convective weather.