A Synoptic Analysis on event of heavy snow precipitation in Gillan Province (2005)

Atmospheric emergency is one of the environmental anomalously phenomenon which damages natural environment and human societies in different places of the world annually.Heavy snow precipitation is one the atmospheric hazards that occurs in cold seasons specially in middle latitudes. In this paper, heavy snow precipitation of Gillan province (2005 February) (Bahman, 1383 AH) has been studied from point of synoptic view. Based on investigation about dry and wet temperature daily parameters and dew point, this fact was distinguished that snow precipitation has happened when these temperatures were around zero degree centigrade or less. Moreover synoptic analysis showed that stabilization of "quasi- blocking" high pressure system in northeast of Caspian sea and west ward mord moving to eastern Europe and at the same time eastward moving of Scandinavian – east of Mediteranean hod and stabilization in north of Iran with oblique shape causes many rains in Caspian basin and then by weakening of couple quasi- blocking system and eastward moving causes penetration of "circumpolar vortex countor" to the region and entrance of cold air from high latitudes and of that area in Gillan province and ultimately causes heavy snow precipitation.