Flood risk map
© NOAA2010 National Hydrologic Assessment
One-third of the United States faces the possibility of "historic flooding" in coming weeks, especially the upper Midwest states of North Dakota, South Dakota, Minnesota and Iowa, government forecasters said.

"Once again we are delivering an urgent message to get ready," John Hayes, director of the National Weather Service, said in a conference call yesterday. "The flood risk is above-average over one-third of the country."

The flood potential is driven in part by El Nino, a warming in the Pacific Ocean, which steered storms that have left the ground saturated from record rains and heavy snows. The area designated for above-average risk stretches from New Mexico to Maine, federal maps show.

"We are looking at potentially historic flooding in some parts of the country this spring," Jane Lubchenco, administrator for the National Oceanic and Atmospheric Administration, said in the conference call.

Many areas of the eastern U.S. have received twice the normal amount of rain in the past three months, said Tom Graziano, a weather service hydrologist.

In Fargo, N.D., where residents are facing an unprecedented second consecutive year of record flooding, sandbags are being stacked to hold back the Red River, and at least two bridges in the state's largest city have been closed.

Officials don't expect the river to get as high as last year's record flood, but near Fargo and neighboring Moorhead, Minnesota, it is forecast to crest Sunday about 20 feet above flood stage. The waters flowing over the river's banks could threaten several houses, roads and parks.

Last year, about 100 homes in the area were damaged and thousands of people were evacuated after the Red River rose above the flood stage for a record 61 days and crested twice. Officials say they are better prepared this year.

"We have over 110 years of records in the Red River valley in North Dakota and Minnesota, and we have never seen back-to-back significant, near-record spring floods," said Scott Dummer, a weather service hydrologist.

Source: Bloomberg News