Abstract:

The sand－dust storm weather occurred on April 24，2010 in the middle of Hexi Corridor was studied．The results show that the strong cold air from the northwest route resulted in this heavy dust storm，it occurred during the process of 500 hPa circulation situation transition from the latitudinal to longitudinal direction．The continual temperature rising provided the favorable thermal condition for sandstorm．The upper and lower level jet stream provided the dynamical condition for it．The exist of dry－warmer area was an omen for its occurrence and it provided abundant sands．The unstable atmospheric structure with warm lower and cold upper was good for the momentum transmitting downwards of the strong wind in upper air．The daily forecast indexes and equations under the different weather conditions were summarized based on the meteorological data from 1969 to 2004 in the middle of Hexi Corridor and the numerical forecast products from 1986 to 2004．The now－forecast indexes were modified and complemented，and it played a well role in the forecasting work of dust weather．

Key words: the middle of Hexi Corridor, gale and sand－dust storm, forecasting method

摘要：

对发生在河西走廊中部2010年4月24日的强沙尘暴天气过程进行了天气成因分析，结果表明:这次特强沙尘暴过程是西北路径的强冷空气引发的锋后偏西大风沙尘暴天气过程，发生在500hPa环流形势由纬向转为经向的过程中;前期持续增温为沙尘暴的发生提供了有力的热力条件;高、低空急流是沙尘暴发生的重要动力条件;干暖区的存在对沙尘暴的发生提供了丰富的沙源并对沙尘暴的发生以及落区有很好的指示性;下暖上冷的不稳定大气层结有利于高空强风动量下传。应用1969～2004年河西走廊中部大风沙尘暴个例资料及1986～2004年数值预报资料，总结归纳出了不同天气形势下大风沙尘暴短期预报指标和预报方程，同时订正和补充了短时预报指标，在业务使用中预报效果良好。

关键词: 河西走廊中部, 大风沙尘暴, 预报方法