...Major Flooding Impacts North Central and Northeast Missouri July 24-25 2008...

A unusual late July weather pattern (one more typical of late May and early June), set the stage for extreme rainfall amounts and major flooding across north central and northeast Missouri.  Hot and humid air, characterized by temperatures in the lower 90s and dewpoints in the lower 70s, continued to feed north across the eastern Plains into western Missouri. Meanwhile, a series of upper air disturbances had brought rainfall to the Mississippi Valley region and northeast Missouri, keeping temperatures much cooler. The reinforced a strong stationary front that was draped from northeast into central Missouri Thursday evening.

 

Graphics depicts setup for extreme rainfall and flash flooding setup

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Although surface temperatures in the upper 60s to mid 70s were much too cool to support afternoon thunderstorms along this front, the airmass aloft remained very unstable. During the overnight hours Thursday and Friday, a stream of strong winds developed several thousand feet above the ground, known as a nocturnal low-level jet. Typically these rivers of fast moving air lead to nighttime thunderstorm complexes in May and June, but diminish as we head into the summer month. However, the current weather pattern actually resembles one more typical of late Spring. As a result, unusually strong winds of 35 to 45 mph developed over eastern Kansas and western Missouri around 2,000 feet above ground level during the overnight hours. These winds transported very warm and moist air into the stationary front, leading to explosive thunderstorm development along the Iowa border. Thunderstorms then tracked southeast along the front, while continuing to regenerate further northwest. The scenario was repeated both Wednesday and Thursday night until the low-level jet diminished the following morning. The result was extreme rainfall amounts, widespread flash flooding, and record river flooding. Rainfall amounts of 6 to locally more than 12 inches fell Thursday night, with Unionville to Kirksville the hardest hit. Extreme rainfall amounts continued along the highway 63 corridor as far south as Moberly.

24-Hour Rainfall, Ending at 7 AM Friday July 25th

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Storm Total Precipitation Ending 7 AM July 25th

 

 


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