WASHINGTON — After an unusually warm winter with low snowfall in much of the United States, no part of the country faces a high risk of flooding this spring, the National Oceanic and Atmospheric Administration reported Thursday in its annual forecast of floods, droughts and spring temperatures.
For many areas, the forecast was a relief after last year's historic floods over many weeks on the Mississippi River in the northern and central parts of the country. This year, the Mississippi and many other rivers have only a normal risk of flooding.
Nationwide, "this is the first time in four years without a high risk of major flooding," Laura Furgione, deputy director of the National Weather Service, said at a briefing.
The only places with above-average spring flood risks are the Ohio River Valley — including parts of western Illinois, much of Indiana and southwestern Kentucky, where there was above-normal precipitation during the winter — and parts of Louisiana and Mississippi.
Still, Furgione cautioned that a heavy rainfall can lead to flooding at any time, even in areas where the overall risk is low. Forecasters only can predict a few days ahead where or how heavily rain will fall.
Floods are a leading cause of deaths from severe weather, and more than half of the deaths are in vehicles, Furgione said. Six inches of moving water is all it takes to lose control in a vehicle.
This year's lower flood potential follows a winter with low snowfall across much of the country. Snow cover across the lower 48 states was the third smallest in the 46 years of the satellite record. (Only 1991 and 1980 had less.) And spring has started early, with March temperatures as much as 35 degrees above normal in many places.
NOAA's National Climate Data Center reported that 400 places had high temperature records broken on Wednesday, and 177 had record-warm overnight lows.
Ed O'Lenic, chief of the operations branch of NOAA's Climate Prediction Center, said it's likely that warm weather will continue this spring, though not at record highs, over the Great Plains, east and southwest. The Pacific Northwest and Alaska are expected to be on the colder side of average.
The dominant force in the weather has been the Arctic Oscillation, the atmospheric pressure patterns in northern middle and high latitudes. Last year the Arctic Oscillation was in a phase that brought low pressure, cold and snow. This year, its other phase occurred, bringing high pressure and warmer and drier conditions, O'Lenic said.
"Extreme events like the one we've seen are consistent with the notion that the climate is changing toward the warmer," he said. Still, he added, it's impossible to connect any single event, like the current record-breaking warmth, with climate change.
Drought continues this spring in the southern Plains, especially in west Texas and eastern New Mexico, as well as in the Southeast, said David Brown, director of the Southern Region Climate Services. Two-thirds of Texas and three-fourths of Georgia are in severe, extreme or exceptional drought conditions — the top three most severe classifications. Drought is expected to continue in many of these areas through the spring, Brown said.
The weather is expected to be wetter than last year's record drought in Texas and Oklahoma. In parts of the Southwest and West, drought is forecast to continue, raising the risk of wildfires. And in Georgia and Florida, drought likely will last a couple more months, he said, at least until the tropical storm season plays out in the summer.
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