The Synoptic Analysis of Heavy Snowfall in Gillan Plain (2014)

Weather and climate events occasionally depending on their size and occurrence can be classified as natural disaster and unexpected that they create serious problems in the process of human life. Including in around of Iran, we are witnessing such events that one of the most dangerous is heavy snowfall days, particularly in the southern part of the Caspian Sea and especially Gillan Plain. One of the heaviest snowfall events at the study region is related to 2014 (1392). This observational study attempts to determine factors responsible for the occurrence of heavy snowfall as well atmospheric circulation at the time of occurrence, also created biological problems.The heavy snowfall that continued for several days had caused a serious disaster in the area. According to the results and identification of the snowy days, synoptic maps at the time of occurrence were prepared and analyzed. The NCEP/NCAR data reanalysis was used to clarify the structure of atmospheric circulation of heavy snowfall over the studied area. Sea level pressure, Geopotential Height, Zonal (U) and Meridional (V) wind, Specific humidity, Omega and Outgoing Longwave Radiation were used to determine the atmospheric circulation of snowfall. The results show that the precipitation has continued in Gilan plane for 5 days (30JAN, 31JAN, 1FEB, 2FEB and 3FEB). Anzali station had the highest and Manjil experienced the lowest amount. The most important factor of atmospheric circulation was strong high pressure formed in the Northern parts of Europe. This high pressure was transformed over the Caspian Sea by the Southward streams. The extreme differences in temperature between the air mass and the sea water had caused the intense convection and strong arising from the area that has led to heavy snowfall. Some of the major problems depending on this natural disaster were serious issues of resident livelihood and blocked roads of towns and villages. So to improve the management of any natural disaster, predicted this natural event early, setting up a comprehensive program to create a proper operational structure with executive ability can fix problems quickly and cause the least damage and casualties.