Why do strong weather phenomena often form near frontal cyclones?

Cyclones bring rain. When they meet cold and warm air masses, the cold and warm air masses are distributed on both sides of the cyclone, and the cold and warm air masses push each other (the northern hemisphere rotates counterclockwise), and the air convection is strong, which together form a frontal cyclone, which usually brings storms and has a certain impact on human production and life.

Note: The continuous heavy rainfall in summer in China is usually frontal cyclone, but the cold wave is not. Cold wave is a combination of anticyclone and fast cold front.