Thunderstorms and tornadoes are most frequently associated with weather patterns that form...

Thunderstorms and tornadoes are most frequently associated with weather patterns that form where maritime tropical air masses interact with continental polar air masses over the United States. Predict where this would be most likely to occur, using Figure 15.6.

Figure 15.6 North American air masses. Principal source areas and paths for air masses that influence weather patterns across North America. Arrows indicate where the air mass moves to after it forms. For example, cP air masses originate in northern Canada and move to the south and southeast across the United States.