عنوان مقاله [English]
One of natural disasters which annually brings about destruction across the world is heavy rain triggered flooding. The present study aimed at identifying dynamic and Synoptic factors influencing the occurrence of heavy rains in Khoram Abad, the provincial capital of Lorestan, Iran, from 2000 to 2005. The relevant data was provided by Lorestan Bureau of Meteorology. Higher-than 30 mm rains were extracted from the data and their pressure distribution patterns at the sea level and weather patterns in 500 and 850 HQP layers were identified by using Grads software. Then, the relationship between heavy rains and weather patterns across different atmospheric layers was investigated. Results of the study indicated that from among the five heavy rain cases selected for analysis two had been triggered by the intermingling of Mediterranean low pressure systems with Sudanese low pressure ones in the studied region. It was also found that the two other ones had been due to the entrance of Sudanese low pressure systems into the country from southern regions of the country and their moisture and heat feed from the tropical and southern waters such as the Persian Gulf. According to the findings of the study, the last case was the result of Black Sea low pressure systems entering the country. The common observation among all the five cases was the presence of a trough, though a weak one, in 500 and 850 HQP layers in order for variation to occur.