Analyzing synoptic patterns of snowfall in Kermanshah

In this Research, the main synoptic patterns affecting snow with an environment-to-circulation approach in Kermanshah station in the West of Iran have been studied. To this end, the daily data of this snow station from January 1951 to December 2004 was collected from Iran Meteorological Organization. Also, to identify patterns of climate, sea level pressure, and temperature data, daily averages of temperature and pressure set of 500 HP data daily mean the reanalysis database by the United States Environmental Forecasting Center on the same date was collected, clustered, and categorized to analyze the temperature and pressure data on atmospheric patterns. Then, by analyzing the maps of all days the number of clusters was determined so that three of them justified the snowfall patterns in the region in the best way. Finally, to identify the most important systems, the combined patterns of sea level pressure and temperature and height and temperature level of 500 of each cluster were drawn and analyzed, forming the basis of this research. The results showed that snow in the west of Iran is affected by different systems near and far in the area, that is 1- formation and strengthening the European high pressure in northwestern of Iran 2- area located on the Mediterranean trough 3- the spread of Polar Vortex of the Southern latitude 4- Strengthening the Siberian High and the Himalayas in the Northeast and East of Iran 5- spread and penetration of Low pressure Sudan to the west of Iran. Consequently, the snowfall of these patterns can be classified in three clusters.1- low snowfall 2- moderate snowfall 3- heavy Snow.When these systems are less severe and extended, low and sporadic snowfall when strengthened, moderate snowfall and when they are at the peak of their activities, heavy snow in this area is witnessed.