The significance of the low-level jet in the development of nocturnal thunderstorms over the Midwest through the production of regions of convergence was investigated for an area centered at Omaha, Nebraska. A composite jet axis representing all non-frontal days during the summer months of 1955, 1956 and 1957 was found to coincide with the line of maximum frequency of thunderstorm occurrence. Correlation between average kinematic vertical velocities and per cent thunderstorm occurrence over the area centered at Omaha supports the view that the occurrence of summer nocturnal thunderstorms is closely related to the production of regions of convergence associated with the low-level jet. Abstract The significance of the low-level jet in the development of nocturnal thunderstorms over the Midwest through the production of regions of convergence was investigated for an area centered at Omaha, Nebraska. A composite jet axis representing all non-frontal days during the summer months of 1955, 1956 and 1957 was found to coincide with the line of maximum frequency of thunderstorm occurrence. Correlation between average kinematic vertical velocities and per cent thunderstorm occurrence over the area centered at Omaha supports the view that the occurrence of summer nocturnal thunderstorms is closely related to the production of regions of convergence associated with the low-level jet.