This research has been conducted with the aim of synoptic-thermodynamic analysis of the patterns leading to heavy convective precipitation in the northwestern region of Iran. For this purpose, the daily rainfall data of 17 selected synoptic stations in the three provinces of Ardabil, East Azerbaijan and West Azerbaijan during a statistical period of 17 years (2000-2016) were used. Among the 63 days with widespread convective precipitation (covering at least 9 stations) in spring, two days were selected as representative days in the region and their precipitation was analysed synoptic-thermodynamically. The criterion for choosing these two days is to cover at least 15 stations and receive at least 50 mm of rain in the maximum core. For synoptic analysis of selected days, from the data of sea level pressure (SLP), geopotential height (HGT), relative humidity, vertical speed (Omega), wind speed, orbital wind component (Uwnd) and meridional wind (Vwnd) level 500 Hectopascal, specific humidity, and precipitable water (PW) were used. Examining the maps and instability indicators led to the identification of two patterns of widespread and heavy rains in spring. The first pattern showed the activity of a strong anticyclone in Siberia and a cyclone around Iraq on the surface of the earth, and a diagonal trough over Syria and its surroundings in the mid-atmospheric level. The second pattern was the influence of the anti-cyclone on the Black Sea at the sea level and the activity of the pseudo-Omega system and its fleet at the upper level. The evaluation of both patterns shows the clear role and existence of dynamic forcings along with local forcings and heating caused by the location in the occurrence of this type of precipitation in the region.