Checking the national radar last evening, one saw pockets of thunderstorms stretching from the Southern Rockies to the Mid Atlantic States. Aligned along a stationary front, these disturbances were moving west to east and, over the past several days, have been impacting the same areas. Since the front marks the southern edge of a broad jet stream trough, the storm waves are energized by strong, upper level winds, increasing their intensity; severe thunderstorms, torrential rains and embedded tornadoes have thus accompanied these disturbances.
As the storms move eastward, they are fed by warm, humid air south of the front and, since they "train" across the same path, flooding has been widespread, especially east of the Mississippi Valley. While monsoon rains are common in the Southwest from mid to late summer, the current jet stream pattern is more typical of late spring; by July, the jet has usually retreated to the north, leaving much of the U.S. in the summer doldrums, relying on "pop-up" thunderstorms to provide relief from the intense heat.
It's safe to say that this storm track will abate when the jet stream moves back toward Canada and hot, humid air moves up from the south; to expect that the jet might move further south, giving the Midwest a cool, sunny August is just wishful thinking. That scenario must wait until October.
