Heavy rainfalls are considered as a risk factor in the occurrence of floods and continuously cause irreparable damages in most areas, including Lorestan province. This study explored the role of interaction between Cut-Off Low (COL) coupled patterns and Polar Front Jet Stream (PFJS) in heavy rainfall event of April 2019 in Lorestan province. In order to achieve this goal, daily atmospheric monitoring parameters (pressure maps, temperature, wind, vorticity, relative humidity, etc.) NCEP/NCAR database with a spatial resolution of 2.5 degrees was used to identify the effective synoptic patterns on the meteorological condition of the studied area, GFS global numerical model overlay maps with a spatial resolution of 13 km was used to compare wind flow with the studied parameters, TRMM satellite precipitation data with a spatial resolution of 0.25 degrees was used to monitor the spatial distribution of precipitation, and observation data of Khorramabad meteorological station based on synoptic meteorological codes were used to analyze the weather conditions during heavy rainfall events. The obtained results show the instability and rise of moist air due to the two forcings of the COL and the PFJS and the convergence of moist currents from three moisture centers of the northern Indian Ocean, the Red Sea, and the eastern Mediterranean. These features provided the synoptic-dynamic conditions necessary for the occurrence of heavy rainfall. However, many other environmental factors like the saturation of the surface layer of the soil due to the high amount of precipitation in the days before the flood have played a role in the aggravation of the said flood.