The strongest satellite evidence yet of a powerful, weather-disrupting El Nino shows that a warm water mass off South America's Pacific coast has grown to 1.5 times the size of the continental United States, NASA scientists said Monday.
Back in May, the warm pool was only two-thirds as big.
In another indication of El Nino's powerful hand, water vapor measurements from another satellite are providing signs that southwestern states could get pounded this winter with storms crossing the Pacific from Hawaii.
An El Nino occurs when westward-blowing trade winds weaken, allowing a mass of warm water normally located off Australia to drive eastward to western South America. The unusually warm water acts on jet stream patterns, altering weather worldwide. The phenomenon got its name from the Spanish words for baby Jesus because the pool usually arrives around Christmas.
Scientists at NASA's Jet Propulsion Laboratory in Pasadena announced in May that satellite data showed an El Nino brewing. Their information provided the basis of a National Weather Service El Nino forecast.
Subsequently, worldwide weather experts said 1997-98 could bring the worst El Nino in 150 years.
``As the satellite has mapped El Nino across the Pacific, what we've seen continually throughout the summer and into September now is that early indications actually have persisted and intensified,'' said Bill Patzert, a research oceanographer with the TOPEX-Poseidon project at JPL.
The TOPEX-Poseidon satellite looks at sea height. Because water expands as it heats up, the higher the sea, the warmer the water.
``For many countries, the El Nino has been here all summer,'' Patzert said. ``In South America, off the north coast of Chile, Peru, Ecuador, they've been hammered with extreme weather because of the presence of high sea levels we see with TOPEX-Poseidon. Indonesia and the Philippines are definitely having severe drought.''
Secondary signs of an El Nino are appearing off North America with warm-water fish migrating north this summer and the fueling of Hurricane Linda, the strongest-ever eastern Pacific hurricane, off Mexico this past weekend.
The warm mass extends eastward from the international dateline, which is about at Midway Island. A radar instrument aboard TOPEX-Poseidon found that expanse of ocean surface is at least 6 inches (15 centimeters) above normal, said Lee-Lueng Fu, the TOPEX project scientist at JPL.
The region peaks off South America where elevations are about a foot (30 centimeters) above normal, Fu said.
That's comparable with conditions during the so-called ``El Nino of the century'' in 1982-83, which brought damaging storms to Southern California, wiping out piers, washing away homes and closing important roads.