An Analysis for a Thunderstorm Weather Event on 28 April 2006 in Shandong Province

Utilizing normal observation data,automatic weather station data,radar rechoes,Satellite images and productions of T213 model out, the thunderstorm event was diagnosed. The results show that the thunderstorm event was caused by a squall line system. In the low level below 850hPa,heating and humidity increasing resulted in THETAse values raising and its high value tongue stretching north to reach the west to Shandong Province. In the high level above 700 hPa, the cold air moved southeast with the THETAse low tongue playing above the low tongue. This caused atmospheric convective instability increasing. The convergence line at 850hPa and trough at 500hPa triggered convective energy releasing whit producing convective cloud cell moving east and developing into a bow squall line sweeping the south parts of Shandong province and bringing thunder rains, gales and hails for its passages.