Study of superheavy Hmdydbarsh Algvh of West and South West Catchment Oromieh Lake

The purpose of this work is the identification and classification of heavy rainfall‘s synoptic patterns with 500Hpa balance in west, and south West drip area urmia lice during the years1366-1390. After determining the time and place threshold of heavy rainfall, first 46 days of heavy rainfall in the region were extracted, then the elevation data with 500hectopascal balance between 5-65 degrees of north latitude and 15-65 degrees – east longitude in the form of S-mode matrix for days of heavy rainfall were set. Next, we clustering and fulfilled this aim by means of ward methods and finally the compound map of atmosphere‘s upper and lower balance related to each cluster were prepared and analyzed synoptically. Our results shows that, during the occurrence of heavy rainfall, eat synoptic patterns were mainly dominant. These patterns are of two major groups: the cut-off low and short waves trough. So that, forward ascending movements of these synoptic systems along with polar front jet stream causes a baroclinic unstable atmosphere in the region and conducts low pressure systems from the Mediterranean, red and partly black seas, from the west, and south West Iran toward west, and south West drip area urmia lice and is crucial for pressure loss the occurrence of heavyrainfall.