Abstract

In this paper for better recognizing of temporal-local behavior of occurred heavy rainfall‚ turned to synoptic and thermodynamic analysis of this rainfall system on 18 to 20 November 2013. For this purpose we extracted and studied daily rainfall data of 8 synoptic stations and the parameters of wind‚ omega‚ humidity‚ HGT‚ for the sea surface levels of 1000‚ 850‚ 500‚ 70hpa from NCEP/NCAR on 18 to 20 November 2013.The results shows that in the rainfall days the Sudan low pressure tongue by one self‚ caused the rainfall of this time. Also in the upper levels the deep trough which obtained from closed cyclone center on south of Iraq with the axis of North-South and east ward moving on half southern of Iran‚ divergence the unstable weather and with falling the cold atmosphere on the Red sea and Sudan and the advection of warm and humid weather by Arabia high pressure which located on Arab sea‚ increased the deepness of the trough and caused the aggravation of southern flows on the located area. Studying the humidity advection maps‚ showed that in the levels of 1000 and 850 hp‚ the Arab sea‚ Red sea‚ Oman Sea and the Persian Gulf had the main role in strengthening and providing the humidity of Sudan low pressure in the rainfall occurrence. But in the levels of 700 and 500 hph only the Red sea and the Persian helped the humidity advection to the rainfall system. Settlement the subtropical jet stream in front of the trough and upper divergence‚ had the main role in strengthening the low pressure and occurrence of all round rainfall in the south of Ian.