Synoptic-satellite analysis of heavy snowfall in Guilan province

Extreme weather events cause serious problems in the normal course of human life due to their scope and time span. Heavy snowfall in the Guilan coastal plain is one of the most dangerous phenomena. In this research, three heavy snows in Guilan province during the statistical period of 1998 to 2018 (20 years) have been analyzed synoptically and satellite. For this purpose, snowfall data were obtained from the Meteorological Organization of Guilan Province, data used for synoptic maps from the NOAA site (NCEP/NCAR reanalysis 1) and satellite images from the Modis sensor site. Then, with the environmental to circulation approach, the synoptic systems were identified according to the origin of formation from a few days before to the day of snowfall. The results showed that three heavy snowfalls were caused by the coordinated expansion of two Siberian dynamic and thermal anticyclone and European anticyclone, bipolar blocking and European high pressure. Also, the study of the snow area by using the Terra satellite Modis images showed that three heavy snowfalls cover more than 70% of the province's area. Therefore, heavy snowfalls in 2005, 2008 and 2017 covered 70.94, 90.44 and 81.46 percent of Guilan province, respectively.