There are 15 numbered regions that have been split into 6 larger geographical regions in order to investigate typical storm reports, which can give us an estimate on impacts from the extreme periods, and seasonality. Which region are you interesting in learning more about?
West Coast : Regions 1 and 3
Great Lakes : Regions 8, 11, and 12
Plains : Regions 7, 9, and 10
Southeast : Regions 13 and 14
Northeast : Region 15
Mountain West : Regions 2, 4, 5, and 6
Within the United States there are trends in maximum number of 14-day periods. The eastern United States, regions 12, 14 and 15, has a maximum of extreme periods during the winter, DJF. The Plains, regions 7, 9 and 10, has a maximum of extreme periods during the spring, MAM. The northwest United States, regions 1, 2 and 4, and the eastern plains, region 11 and 13, both have a maximum within the fall, SON.