Flood of 1997

Violent storm took
unusual detour

The Cincinnati Enquirer

An unusual weather pattern about 25,000 feet above the Louisville area directed the path of the rainstorm that devastated Southern Ohio and Northern Kentucky.
Cincinnati was largely spared for one simple reason: luck.


Glaciers made cities safe from water
Graphic: River's
rise and fall

Graphic: Anatomy of the storm, (PDF, 215k),
(JPEG, 257k)
Graphic: Flood gates provided protection, (PDF, 88k),
(JPEG, 105k)
''We knew it was going to rain, but what surprised us was the amount,'' meteorologist Steve Wilkinson of the National Weather Service in Wilmington, Ohio, said March 2.
Cincinnati received .94 inches of rain the night of Feb. 28, 1.39 inches March 1 and .17 on March 2.
By contrast, areas of Brown and Adams counties, about an hour's drive east from Cincinnati, got an estimated 8 to 10 inches.
The thunderstorms were part of a broader system that caused several deadly tornadoes in southeastern Arkansas and northwestern Mississippi. Normally with a low-pressure system, rain tapers off as the warm front moves north. However, a diffluence above Louisville pushed the storm northeast, setting its path inland and south of Cincinnati.
A diffluence occurs when high-atmosphere winds are blowing away from each other. When there is high-moisture air below the diffluence, the combination causes a sharp increase in precipitation, Mr. Wilkinson said.
''This event isn't unusual by itself, but with everything coming together, it can be very dangerous,'' Mr. Wilkinson said.
The massive storm capped several weeks of rainfall over large regions of the river basin. Experts say that combination is what caused the Ohio River to flood.
At its peak March 5, the Ohio River at Cincinnati was pushing 690,000 cubic feet of water per second. To give a sense of scale, the Licking River that swamped Falmouth was moving at about 100,000 cubic feet per second at its peak March 4.
The good news for Cincinnati was that the worst of the rainfall -- more than a foot in some places -- fell downstream in Kentucky.
Had the huge downpours fallen farther upstream, then the worst flood in 33 years may have been the second-worst flood ever in Greater Cincinnati -- with river levels well above 70 feet, experts said.
''Cincinnati was north of where it happened, just lucky,'' Mr. Wilkinson said.

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