El Niño-like phenomenon means dry years ahead in U.S.

Dry conditions in the southern part of the U.S. are predicted due to the PDO phenomenon

January 19, 2000
Web posted at: 4:22 p.m. EST (2122 GMT)

From Correspondent Anne McDermott

LOS ANGELES (CNN) -- Remember El Niño? It only lasted for just over a year or so, but it made life miserable for many. Now scientists say there's another system forming in the Pacific that's much larger and could have dramatic impact on U.S. weather for several years.

The phenomenon this time is a natural climate pattern called Pacific Decadal Oscillation (PDO), identified by warmer-than-normal ocean water in a sort of horseshoe shape, with a wedge of cool water pushing inside.

It has been developing slowly but surely, and experts say the PDO's effect on the jet stream could alter North America's climate for a decade or more.

	MESSAGE BOARD
Global climate
	VIDEO
CNN's Anne McDermott explains the weather phenomenon known as PDO. Real 28K 80K Windows Media 28K 80K

That might mean above average rainfall in the northwest and low rainfall and periods of drought in the southern part of the nation.

Scientists say the PDO phenomenon, which isn't related to global warming, has probably been around forever, but it was difficult to study until the advent of advanced satellite technology.

Scientists now know that PDOs grow, then shrink, over the course of 20 to 30 years. Then the cycle begins all over again.

While the current PDO will mostly be felt in the United States, it may have been involved in the deadly flooding that hit Venezuela in the past year and the devastating wind storms that hit Europe last month.

Mostly, the PDO means it's going to be drier in much of the United States. But it's doubtful it will be so dry that people ever refer to El Niño as the good old days.

Note: Pages will open in a new browser window

External sites are not endorsed by CNN Interactive.