Final answer:
Maritime air masses from the North Atlantic are of limited concern for U.S. weather primarily because prevailing winds tend to move these air masses east towards Europe, and the temperate climate of the region influenced by the Gulf Stream does not typically generate severe weather patterns that would impact the U.S.
Step-by-step explanation:
The question why maritime air masses from the North Atlantic are of only limited concern for weather in the U.S. can be answered by recognizing the role of prevailing winds.
These air masses are usually moved away from the U.S. due to the predominant wind patterns. More specifically, in the Northern Hemisphere, the general circulation of the atmosphere tends to move air masses from west to east due to the rotation of the Earth and the Coriolis effect. Thus, the weather systems and air masses that form over the North Atlantic are typically pushed towards Europe rather than the United States.
Additionally, the temperate climate of the North Atlantic, influenced by the Gulf Stream, does not typically produce extreme weather that would affect the United States. While maritime climates are known for their milder temperatures and fewer extremes, the types of severe storms that could impact the U.S. mainly originate from different areas, such as the tropical regions where hurricanes can form and potentially travel northward along the eastern seaboard.