The extreme cold precipitation is solid precipitation in cold season. In order to manage of disaster resulted from extreme cold precipitation, forecasting of this event is essential in mountainous regions. At present research, synoptical mechanism during coupling Mediterranean and Sudanian systems are investigated in Iranian western regions. For this purpose, synoptical stations at Zagros region and NCEP/NCAR reanalysis data are used. Using GrADS software, synoptic maps are plotted. Investigation of the synoptic maps shows that occurring of the extreme cold precipitations resulted from coupling Mediterranean and Sudanian systems. During the coupling of the Mediterranean and Sudanian systems, a lot of humidity converges that causes the aggregation of the humidity.