Synoptic Analysis of Intensive Daily Precipitation in The Larestan Area of Iran

In order to analyze the synoptic origin of precipitation of the Larestan area, the rain days with more than one millimeter rain were obtained from the Iranian Meteorological Organization for the 1960-2007 periods. First the wet periods of 1-6 days long were determined. From these wet periods the most intensive and longest rain period during both cold and warm seasons were identified as February 1993 and July 1995. The synoptic systems producing these rain periods were extracted from the 12 GMT surface and 700 hPa and 500 hPa maps. The results of the study showed that the main pressure patterns of these rains are westerly cyclones, Sudan low, and upper level troughs during cold season. But during summer season the Monsoon and weakening Subtropical High are main pressure patterns.