Synoptic analysis of devastating floods July 2015 in north of Iran

Dreadful and torrential precipitations in the summer cause heavy damages in the sections of constructive and agricultural installation in different regions of the country because of their unexpected. In this research we proceed to synoptic and thermodynamic of torrential flooding of 28 to 31 july2015 in the half north, west and central of the country. First with using territorial stations data the precipitation of under studied stations analyzed and then with using upper atmospheric data and tracing the related maps, precipitations analyzed. The results showed that spreading the black sea high pressure on north half of the country and penetrating the Warm low pressure of Persian Gulf-Pakistan from south, meanwhile, northern flowing cause severe gradient pressure in the sea level. In the middle levels stretching the trough axis from central Asia till south of Iran cause severe ascending of air. Analyzing the omega maps on Iran indicates the settlement of maximum negative omega in north of Iran. Also analyzing of moisture advection showed that in the levels of 1000 and 850HPA, the black and Caspian seas are the sources of supplying moisture. But in the levels of 700 and 500 HPA, the Oman and Arab Sea and India peninsula has the main rule in transferring the moisture on the studied region.The point worthy of attention is that the jet stream located only above the level of 300 hpa and upper the latitude of 38 northern degree and out of the occurrence boundary of supper heavy precipitation of ending days in July 2015.And it's impact was indirect which caused offloading the warm and humid air to the through and consequently strengthen the instability.