Although winter precipitation in south-east of Iran is a random phenomena, but in particular synoptic conditions, heavy precipitation occur in this area. This type of precipitation are very valuable for local people. Studies of eight precipitation systems during 1380-1382 indicate that there are two general precipitation patterns in South-east of Iran. In pattern type A, two anticyclone centers, one over north of Black Sea and east of Europe and the other in east of Aral lake are present; troughs of which combined together and its southern trough is spread over east of Mediterranean to North Africa. In pattern type B, one anticyclone occurs over Aral lake and another occurs over Atlantic ocean and west of Mediterranean and its trough covers all over Mediterranean and north Africa up to Egypt. In both cases, and with regards to weather conditions in upper atmosphere, low – pressure system over Sudan turns towards east and from south-east enters to Iran.

Keywords: Synoptic Pattern, Precipitation, South-east, Sudan law, Winter Precipitation

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