La Nina Is Back: Cue Another Weird Winter

Winter looks to be cold and wet across the northern tier of states, and the drought will worsen in the South, where conditions are expected to be warmer and drier than usual, government forecasters said today. Like last winter, the Pacific Ocean cooling known as La Nina is affecting the weather, according to the National Oceanic and Atmospheric Administration. Mike Halpert, deputy director of the agency's Climate Prediction Center, said snowfall probably will top the usual amounts from the Northwest to the Great Lakes and the Ohio and Tennessee river valleys.

Some specifics:

• Northeast and Mid-Atlantic: Equal chances for temperatures and precipitation above, near, or below normal. Winter weather in these areas is often driven by a pressure change called the Arctic Oscillation, which is difficult to forecast. If enough cold air and moisture are in place, areas north of the Ohio Valley and into the Northeast could see above-average snow.
• Southern Plains and Gulf Coast states: Warmer and drier than average; will probably worsen drought conditions.
• California: Colder than average with odds favoring wetter than average conditions in northern California and drier in southern California.
• Ohio and Tennessee Valleys: Wetter than average with equal chances for temperatures above, near or below average; potential for increased storminess and flooding.

(More La Nina stories.)