To understand why severe weather has been constant factor for folks in the southeast over the past couple of weeks, we first need to understand the jet stream and the role it plays.
Cold air from the North Pole, and warm air near the equator, they generally come together over the United States and Canada and force upper level winds in the atmosphere to move pretty quickly. That's the jet stream here and it's typically parked roughly over the lower 48 as we head into autumn. That will bring chances for storms into the midwest to deep south during the transition between summer and winter.
Further into winter, that cold air pushes farther south as the jet stream pushes farther toward the equator as well.
That brings more cold and wintry weather to folks, but as the jet stream jumps back north in spring it brings back the chance for storms in some of the deep south.
That's the pattern we find ourselves in lately. Where the flooding is expected to be a concern today, the Jet stream lines up fairly well.
If we look towards tomorrow, the flooding risk pushes east along with the winds aloft.
Not coincidentally, we find the severe storm risk in the same vicinity for Tuesday afternoon.
At a very basic level, we can tie this pattern to where the jet stream lies, which in turn can be tied to our seasons, or how much the northern hemisphere is tilted towards the sun.