Weaker El Niņo 'has arrived'

NOAA plans to track phenomenon for changes

A network of buoys across the Pacific monitors temperature changes.

CAMP SPRINGS, Maryland (CNN) -- It's back. Rested, ready -- and weaker than its 1997-98 predecessor -- El Niņo has officially returned, government scientists said Thursday.

Climate researchers at the National Oceanic and Atmospheric Administration (NOAA) cited several consecutive months of abnormally warm ocean temperatures in the mid-Pacific Ocean, and heavy rainfall along South America's Pacific Coast -- both signs that the global weather phenomenon is upon us.

"This time around, El Niņo will not be as powerful as the 1997-98 event, but we'll track it closely for any change in its projected strength," said NOAA climate specialist Vernon Kousky in a written statement.

El Niņo weather conditions tend to emerge about twice a decade, when a convergence of weather conditions prompt water temperatures to rise in the Pacific Ocean along the equator.

EXTRA INFORMATION Notable effects attributed to El Niño in 1997-98  Interactive map: El Niño episodes around the world  Fact Sheet: Charting El Niño

The temperature changes trigger a meteorological domino effect, altering air and water currents over much of the globe. El Niņo conditions typically bring dry weather to Southeast Asia, torrential rains to Peru and Chile, and a variety of different impacts to the United States. NOAA has not yet offered predictions on the extent of U.S. impacts for this year, though.

In the 1997-98 El Niņo, rain and winter storms triggered mudslides on the California coast; unusual snowfall hit the desert Southwest, and a warm, wet winter greeted much of the East and Gulf Coasts.

While the South American impacts have already hit this year -- record rains inundated Santiago Chile two months ago -- the United States often does not see much El Niņo impact until winter.

Not necessarily bad

Not all of El Niņo's impacts are necessarily bad; high-level winds from the weather system tend to cut down the number of Atlantic hurricanes.

A June 2001 NASA satellite image shows what may be the beginnings of an El Niņo.

NOAA maintains and monitors a network of buoys across the tropical Pacific Ocean as an "early warning" system for signs of developing El Niņo conditions. The buoy network was set up after El Niņo-inspired storms took the California coast by surprise in 1983, causing millions of dollars in property damage from floods and mudslides.

Despite intensive research in recent years, little is known about how and why El Niņo conditions develop. But climate historians have tracked evidence of El Niņo conditions for centuries.

Its name comes from Peruvian fishermen, who christened the phenomenon "El Niņo" after noticing changes in water temperature and in their fish catch around Christmas.

The Spanish name for the Christ child is "El Niņo."