Synoptic Analysis of Heavy Precipitation Events in Iran

In this research, one of the heaviest and over spreading precipitations of Iran (from 3/11/1994 up to 8/11/1994) was studied for understanding and knowing the effective mechanism on occurrence of such events. In this period, about half of Iran's rainfall stations had a remarkable precipitation. For analyzing this event, environmental circulation pattern was selected. After drawing the isohyetal maps of the under studied days, peak points of rainfall and gravity centers were obtained and then the main circulation pattern and humidity sources at the time of these events were obtained. Analysis of pressure maps of sea elevation showed that European's high pressure and Iraq's low pressure pattern has been effective in occurring such rainfalls. At that time, a high pressure mass from Europe and Black sea was entered from north west of Iran and with Iraq's low pressure made a server gradient. It seems that under this intensive pressure gradient and also integration of tropical and polar front on Iraq, deep falling on Cyprus, moisture feeding of Persian Gulf on elevations of 925 and 850 Hectopascal, moisture feeding of Red sea and Mediterranean in higher elevation, these heavy rainfalls has been occurred.