Almost half of U.S. faces spring flooding: NOAA

WASHINGTON/CHICAGO Thu Mar 17, 2011 3:08pm EDT

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WASHINGTON/CHICAGO (Reuters) - Almost half the United States -- the North Central region, the Midwest and the Northeast -- faces a high risk of spring flooding over the next two weeks, government forecasters said on Thursday.

The National Oceanic and Atmospheric Administration said in its spring forecast that the stage was set for potential widespread, record flooding, particularly in the North Central United States for the third year in a row.

"With spring flooding already underway over portions of the U.S., NOAA forecasters are warning the worst is yet to come," the forecasting agency said.

The top spring flood risks include the Red River of the North, which forms the state line between North Dakota and Minnesota, and the Milk River in eastern Montana, NOAA said.

Much of the flooding will be due to warmer temperatures that cause a large part of the snowpack in the North Central region to melt, NOAA said.

The warning follows one of the snowiest winters on record for the northern United States.

The upper Midwest crop belt had its second straight year of above-normal precipitation, with several areas receiving twice their normal snow and rain from December to February, Steve Hilberg, director of the Midwestern Regional Climate Center, told the Reuters Global Ags Forum on Thursday.

(Graphic r.reuters.com/tab48r)

The main early danger from this flooding, and expected above average rainfall, is that soggy fields will delay farmers' spring field work, government forecasters said.

Grain traders and farmers often read a delayed planting season as a drag on final crop yields in autumn.

The huge snowfall and heavy snowpack is also reminding them of the massive flooding that can hit the top U.S. grain producing regions -- as with the Red River Valley in Spring 2009 and throughout the northern Midwest Corn Belt in 2008.

Hilberg said the Red River was under the greatest risk of a repeat.

"In the Red River Valley, it certainly is possible. A significant rain on top of the snow would cause a huge amount of runoff. There is currently about 4-6 inches of water in the snow," he said. "Over the remainder of the Midwest, flooding along the lines of 2008 is probably not likely."

Other areas facing flooding risks: the James and Big Sioux rivers in South Dakota, the Minnesota River, the upper Mississippi River basin from Minneapolis southward to St. Louis, and a portion of lower New York, eastern Pennsylvania and northern New Jersey.

NOAA also said that the La Nina weather pattern, which generally brings dry U.S. weather conditions, peaked during the December-January period, but will remain moderately strong in April and then weaken by June.

(Editing by Walter Bagley)

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