The persistent heat and drought in the Southeast and the record floods across the Upper Midwest are related to the same weather system. As mentioned in a few of my earlier blogs, a ridge of high pressure has been sitting over the lower Mississippi Valley and Southeastern States for most of the summer, deflecting Pacific and Canadian fronts to the north. Within the dome, air is sinking, heating and drying out, resulting in triple-digit temperatures and an unrelenting drought.
As excessive moisture was injected into the Southern Plains by the remnants of Tropical Storm Erin, it was swept northward along the western rim of the dome. Once in the Northern Midwest, this moisture spread out along a stationary front that was held in place by the high pressure ridge to the south. Pulses of low pressure, moving along the front, have produced recurrent, heavy rains, which move across the same swath of ground. The results: phenomenal amounts of rain and widespread flooding from Minnesota to Pennyslvania.
