One of the primary features during late summer--actually, the leading feature for the Corn Belt--was the setting-up of a huge area of hot high pressure over the south-central Plains, southwestern Midwest and the Delta. We know what happened underneath this high--it got blistering hot and dry. The height of this feature in the atmosphere, and the lack of any ability of storm systems to punch through it, brought on the nickname "Dome of Doom". I discussed this development in detail during the Farm Progress Show in Decatur, Illinois and Husker Harvest Days near Grand Island, Nebraska.
The "Dome of Doom" was a crop-wrecker during its sojourn over the Corn Belt, but it was also a co-conspirator of sorts in the horrific heavy rain and flooding that inundated the Front Range area of Colorado in mid-September. Here's why the "Dome of Doom" was such a key player in that tragedy as well:
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During the week to ten day period after Labor Day, the huge high-pressure dome re-located from the Kansas-Missouri area farther south and east, into the Deep South--Alabama, Georgia, South Carolina. And there it stayed. Did the dome bring some heat to the Delta and the Southeast? It certainly did. But, it did something else, too--it blocked the progress of any storm system forming in the southwestern U.S. from moving eastward, while continuing to rotate (clockwise motion) moisture from the Gulf of Mexico northwestward into the upslope area of the southwestern Plains.
At the same time, a former Pacific tropical weather system, known as "Lorena", formed on the Mexican coast near Baja California and stalled out. With counterclockwise air flow around this tropical system, moisture from the eastern Pacific got funneled northeastward into--again--the upslope area of the southwestern Plains. Add in some periodic upper-air disturbances traversing the western U.S. which typically occur, and the stage was set for the powerful, historic flooding rains that formed in the Front Range of Colorado.
Would this destructive rain have occurred without the "Dome of Doom" influence to the east? Well, there certainly would likely have been some rain, but to such an incredible volume, no.
Sometimes the atmosphere does peculiar things. In this case, the "Dome of Doom" was a damaging feature in two tremendous late-summer weather events.