Using data from automatic weather stations, precipitation phenomenon instrument, marine buoy station, ship observations, lightning location observation data , wind profile radar, dual-polarization radar, the FY-4B satellite, and ERA5(European Center for Medium-Range Weather Forecasts Reanlysis v5, ERA5) reanalysis data, this study analyzed the causes of a rare strong Cold air outbreak snowfall event that occurred in the Bohai Strait on December 7, 2024. The results indicate that: (1) The center of this strong snowfall was located in the Bohai Strait, accompanied by significant lightning activity. (2) The snowfall occurred under a synoptic situation where a transverse trough behind an upper-level cold vortex became vertical. A mesoscale vortex in the lower troposphere enhanced upward motion, providing favorable dynamic conditions for the heavy snowfall. (3) During the occurrence of cold-air outbreak-induced heavy snowfall, the instability in the lower atmosphere intensified. Buoy station data indicated an increase in the sea-air temperature difference and a surge in sensible heat flux. (4) Lightning and heavy snowfall occurred during the mature stage. The lightning occurred after the strongest upward motion, and the peak lightning frequency coincided with the timing of maximum snowfall intensity. Wind profile radar data indicated that surface winds shifted from Westerly to southwesterly to northerly when lightning occurred. (5)The lightning location was mainly on the north side of the ground mesoscale convergence line, and it was primarily located within radar reflectivity exceeding 30 dBZ near the vortex center. (6)The air during the snowfall period contained abundant supercooled water, and riming phenomenon was observed. Snowfall particles exhibit a bimodal size distribution, characterized by the coexistence of graupel and aggregated snow crystals. Graupel particles exhibit intermittent occurrence characteristics.? Lightning occurred in areas adjacent to regions with high graupel particle concentration. the characteristics of the cloud particles satisfied the conditions for the non-inductive charging mechanism.