Climatic Monitoring of Snow Days in Zahedan

In this regard, the present study investigated the climatic of the Zahedan snow days since 1976 over a period of 40 years. To achieve this goal, two databases were used. First databases; the present weather codes are related to the snow phenomenon, which was collected daily from the Meteorological Organization. The second database, relates to the daily data of sea level pressure and geopotential height in the troposphere from National Center for Environmental Prediction (NCEP). With Environmental to Circulation Technic and cluster analysis, weather patterns causing snow days, identified. The results of the analysis showed that, snowfall in Zahedan is concentrated in autumn and winter seasons (December, January, February and March). At sea level pressure, integration patterns of Siberian-Caspian high-pressure migrants with 32.5% and Siberian-Caucasian highs with 20%, play the most roles in snowfall event. Also in the middle troposphere, Turkmenistan's ridge and Blocks (cut-off high) account for 42.5% and the European omega block pattern accounts for 25% of the snowfall frequency. It seems that the simultaneous activity of atmospheric disturbances in the immigrant high pressure systems of the Siberian, European, Caucasian, Russian and Caspian, deep ridge polar latitudes and its extension to the lower latitudes, It will exacerbate showers and temperatures, cold weather and snowfall.