A double-barreled region of high pressure thousands of feet above the ground spent much of the summer with one center over the Four Corners and another over Bermuda. The clockwise circulation around these high-pressure domes regularly pumped moisture from the Gulf of Mexico and tropical Atlantic up the East Coast. This favorable setup paired with persistent low pressure over the Great Lakes, which helped lift the air, supported severe weather over the Northeast, time and time again.

Source: Washington Post September 27, 2021 18:21 UTC