Flooding from a weather rut of clashing air masses

[June 16, 2008]  WASHINGTON (AP) -- Hot sticky air hovers on the East Coast. Cool air is parked in the West. And when they repeatedly collide, it storms over an already saturated Iowa.

This has been the stuck weather pattern for weeks and it's led to tornadoes, thunderstorms, heavy rain and eventually record flooding.

Add to that La Nina in the Pacific Ocean, which some meteorologists think could be a factor. La Nina, which is the cooler side of El Nino, causes changes around the world, including more rain and snow in some of the Midwest. Even though La Nina itself is falling apart, its effects may still be felt in Iowa and Wisconsin.

Iowa's rivers and land probably could have handled the massive rain -- more than 15 inches in the last two weeks in some places -- if it weren't for the heavy snow in the winter and lots of rain in the early spring, said Rob Middlemis-Brown, director of the U.S. Geological Survey Water Center in Iowa City.

"The ground never dried out," he said.

That ground was saturated, rivers were already high when the latest batch of concentrated localized storms started in late May, leaving water nowhere to go but over river banks.

The Cedar River, like other flooding rivers in Iowa, eventually dumps into the Mississippi. The National Weather Service issued moderate to major flood warnings Friday for much of the middle Mississippi River region.

For parts of Iowa and southern Wisconsin, this year's flooding is worse than the 1993 great Mississippi and Missouri river floods, said Ken Kunkel, interim director of the Illinois Water Survey. More rain is falling and in a shorter time now than in 1993. But for the entire Midwest, it was worse 15 years ago, he said.

That's because this year's flooding -- while it has the same weather pattern as 1993 -- is much more concentrated and localized in the Iowa, Wisconsin, Minnesota, Illinois, Indiana region, Kunkel said. The flood 15 years ago was over a wider geographic area and lasted longer.

But give this year more time, he added. The 1993 flooding peaked in July and August. It's only early June, so flooding for the broader region could be as bad as 1993 or worse if current patterns hold, Kunkel said.

The good news is that after rains continue on-and-off through Sunday night, close to a week of dry weather is predicted, said Steve Hilberg, director of the Midwest Regional Climate Center in Champaign, Ill.

However, it's still too early to tell if that weeklong respite will be just a break or a real change in the weather, he said.

[Associated Press; By SETH BORENSTEIN]

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