Abstract:By using conventional data and simulation results from models of European Centre for Medium Range Weather Forecasts (ECMWF) and Chinese Unified Atmospheric Chemistry Environment Dust (CUACE/Dust), the weather situation, causes and forecasting results of the sand and dust weather process from 27 to 30 March 2015 were analyzed. This sand and dust weather in North China and Huanghuai Region of China resulted from the southward moving of cold air caused by rapid changes of northeast cyclone. And then, active warm air from southern regions brought the dust back to the north. Forecas ters’ inadequate estimation to the rapid changes of weather situation and the missing forecasting of the dust from the northern path by numerical models led to the underestimation of the strength and coverage area of the dust storm in North China and Huanghuai Region of China on 28 March. Moreover, the back transport of dust from south to north was not fully considered by both forecasters and models, especially in haze days. Thus, dusty, hazy, and the mixed weathers should be identified by observing the concentrations of PM10 and PM2.5 in spring, and pollution types could be judged by whether the primary pollutants were PM10 or not.