Odd Weather May Be La Nina Effect, Scientist Says

The nation’s weather seems out of whack, with unusually cool temperatures in parts of the West and unrelenting heat in the East. And the ocean that spawned El Nino and its deadly storms may be to blame, an expert said Tuesday.

Unusually warm Pacific Ocean temperatures off Asia and abnormally cool water off North America are shoving the jet stream farther north, said Bill Patzert, an oceanographer with NASA’s Jet Propulsion Laboratory in Pasadena.

That keeps the West Coast cool and prevents air masses from bumping into each other. And that means no thunderstorms or other rain.

During the El Nino winter of 1997 and 1998, the equatorial Pacific was unusually warm and sucked the jet stream and storms southward, Patzert said. California and the southern-tier states were pummeled.

“Now we have a flip-flop situation where the eastern Pacific is very cool,” he said. “When the jet stream is farther north--north of the Great Lakes--it robs the Mid-Atlantic, Midwest and the Southeast of . . . normal rainfall.”

In the East and Midwest, a heat wave has been blamed for scores of deaths in 18 states. Crops are withering and forest fires erupting as a drought persists.

The latest phenomenon, observed by the U.S.-French Topex-Poseidon satellite, may be an effect of La Nina, a pool of cool water along the equator. La Nina developed after the 1997-98 El Nino, or unusually warm water along the equator.

The Pacific, which covers 45% of the Earth, fuels the weather across North America as water and wind mix along its vast surface.

The complex interaction affects not only ocean temperatures but also air moisture and storm paths over the continent.

Other experts aren’t so sure about Patzer’s theory.

“Obviously the North Pacific is playing a role, but how big a role it is--especially in the summertime--we don’t know,” said Robert Livezey, senior research meteorologist for the National Climate Prediction Center. “It’s an open question.”