WASHINGTON (AP) - Next winter should be cool and wet in the South and warmer than normal in northern areas, according to government researchers studying a developing phenomenon called El Nino.
Characterized by a warming of parts of the Pacific Ocean, El Ninos occur every few years and can affect weather worldwide.
Strong El Nino conditions are currently developing in the tropical Pacific, the National Oceanic and Atmospheric Administration reported Tuesday.
"This El Nino event is shaping up to be similar to the strong events of 1957, 1972 and 1982-83. During those years, many sections of the southern half of the United States, including California, experienced above normal rainfall from September through the following May," said Ants Leetmaa, director of the federal Climate Prediction Center.
Named for the baby Jesus because the phenomenon usually becomes noticeable around Christmas time, El Nino is the name scientists use for the warming trend and resulting shifts in wind and weather patterns globally.
Warm, moist air rising from the Pacific disrupts the normal flow of the strong upper air jet stream winds that steer weather patterns around the world.
The possibility of a new El Nino was first reported by NOAA scientists in mid-May and confirmed by NASA researchers by the end of that month.
Leetmaa said the researchers expect the result to be wetter, cooler weather for the southern half of the United States from November through March, while the northern part of the country from Washington east to the western Great Lakes will experience warmer than normal temperatures.
Things are harder to predict for summer, a season in which the effects of El Ninos are inconsistent.
But these events can have impacts worldwide, including increased rainfall across the southern tier of the United States and in Peru, sometimes resulting in destructive flooding; and drought in northeast Brazil, southeastern Africa and the west Pacific.
The warm water and thunderstorms in the Pacific Ocean can cast a deadly shadow on weather worldwide. A severe El Nino in 1982-83 was blamed for 1,500 deaths and damage totaling up to $8 billion.
El Ninos usually occur approximately every two to seven years.
Predicting the arrival or departure of an El Nino is critical in helping water, energy and transportation managers and farmers plan for, avoid or ease potential losses.
For example, NOAA's National Marine Fisheries Service expects the ocean warming off California caused by the summer arrival of El Nino to bring bonus fishing for southern California anglers but lean times for other fisheries, including salmon and rockfish and for certain marine mammals.
"If the El Nino episode strengthens, we should see tropical and temperate marine species shift northward beyond their normal ranges, and other changes in marine life," said William Hogarth, acting regional administrator of the fisheries service's Southwest regional office in Long Beach, Calif.