El Niño forecast to keep isle winter dry
The Pacific warming could also extend the hurricane season
A weak El Niño that's developed in the tropical Pacific may become moderately stronger over the next few months, creating some hazards and problems for isle residents, weather officials report.
They predict drier-than-normal weather from mid-December through March, which particularly will affect farmers and ranchers, potentially dangerous high surf on north shores, and possible flash flooding even in a drought and an extended hurricane season.
El Niño phenomena drive worldwide weather changes and are associated with abnormal warming of surface ocean temperatures in the eastern tropical Pacific and an oscillation of the ocean/atmosphere system.
A network of moored buoys shows sea surface temperatures have increased about 2 degrees in the Central Pacific and 3 to 4 degrees in the East Pacific, said Jim Weyman, Central Pacific Hurricane Center director and meteorologist in charge, National Weather Service Honolulu Forecast Office.
"It sounds like a small change, but it's a huge difference over a great expanse of ocean," he said. That much warming results in tremendous energy, which is why El Niño disrupts weather globally, he said.
Weyman said there are some signs of the current El Niño gaining strength, "but nothing like the 1997-1998 El Niño, one of the strongest of the last 50 or 60 years. It's unlikely to go much above moderate."
Even so, the climate phenomenon will have an impact, Weather Service and U.S. Geological Survey Hawaii officials described yesterday in a "winter weather outlook for Hawaii."
After record rains from Feb. 20 to April 2, many island areas had near to below normal rainfall, they said. Drought occurred in Upcountry Maui, west Molokai and Waimanalo on Oahu, all agricultural areas, resulting in some irrigation water shortages.
From now through December is a critical time for rain and some areas already are getting less than half of their normal amount, said Kevin Kodama, senior service hydrologist in the forecast office.
If this continues, he said, agriculture and ranching areas will be in a lot of trouble. Demands on irrigation will be high and "there is already more stress on diminished supplies," he said.
The possibility for a late season hurricane also is greater, Kodama said. "We have to be vigilant ... especially with El Niño in the background."
The hurricane season usually runs from June through November and peaks in September. But Hurricane Iwa occurred in late November in 1982 during a strong El Niño, Weyman pointed out.
Kodama cautioned the public to remain alert to flash floods, recalling a big flash flood on Oahu in December 2003 during a weak to moderate El Niño.
"It just takes one flood event to affect you personally," he said, citing the risks to property and lives.
"And tell people do not drive through flooded roadways," Kodama added. "Turn around. Don't drown."
Rick Fontaine, USGS Hawaii hydrologist, pointed to the dangers of fast-rising streams and flooding. He said flooding occurs mostly in the winter but can happen at any time.
Streamflow conditions probably will be below average with El Niño conditions, he said, "but that does not mean we won't get floods."
And historically, far more extreme floods have occurred than anything that has happened in recent years, he said.
For example, as damaging as the 2004 Halloween Eve flood was in Manoa Valley, an even bigger flood occurred there in the late 1960s, Fontaine said.
The University of Hawaii-Manoa's climate center, the International Pacific Research Center, also issued a report yesterday saying El Niño will become stronger over the next two months based on conditions in the Indian Ocean.
Shang-Ping Xie, meteorology professor, and H. Annamalai, atmospheric scientist, found that cooling in the eastern tropical Indian Ocean weakens atmospheric convection over the region, sending atmospheric (Kelvin) waves along the equator to the Pacific. These waves cause anomalous westerly winds, which are associated with a growing El Niño, they said.
