The 2020 hurricane season may be best remembered as the one that spawned so many storms that forecasters ran out of names and had to resort to Greek letters. But it is notable for another disquieting reason: the number of storms that developed in the mid-latitudes right off the U.S. coast. While this is not unheard of, it is unusual. And it may become more frequent as climate change alters hurricane behavior, according to a new study.