El Nino heralds more isle storms


POSTED: Friday, July 10, 2009

El Nino's return to the Pacific after a four-year absence changes the hurricane season forecast from near to below normal for tropical storm systems to above normal, says Jim Weyman, Central Pacific Hurricane Center director.

An El Nino (meaning “;the boy”; in Spanish) occurs every two to seven years with warming of ocean water in the central and eastern tropical Pacific, a phenomenon that significantly affects global weather and ocean and fisheries conditions.

“;As we have seen before with El Ninos, it does often mean more tropical cyclones in the Central Pacific,”; said Weyman, meteorologist-in-charge of the Honolulu Forecast Office. The top four seasons for high activity in the Pacific were “;twice as normal and almost all El Nino years,”; he said.

Central and eastern Pacific waters have warmed at least one degree above average, and warming is expected to continue at about that level through early winter according to models, Weyman said. Warm ocean temperatures fuel and strengthen hurricanes, according to the National Oceanic and Atmospheric Administration.

He urged islanders to be prepared for a potential “;increased threat as we go through summer and into the fall.”;

A strong La Nina (Spanish for “;the girl”;) occurred in the Pacific in the past year with unusually cold sea-surface temperatures that began weakening in spring, Weyman said, warming rapidly in early summer.

Weather officials had predicted an 80 percent chance of average or below-normal storm activity and a 20 percent probability for above-normal activity for this year's hurricane season, which began in June and continues through November.

El Nino's development pushes the forecast “;into that probability of above-normal season,”; Weyman said.

There is also a greater possibility of late-season tropical cyclones, less rainfall during the wet season and more high surf on the North Shore, he said.

Kauai suffered heavy damage from Hurricane Iwa in November 1982 and from Hurricane Iniki in September 1992. Both were El Nino years, Weyman said.

He said the Central Pacific normally averages 4 1/2 storm systems during hurricane season. In 1992 there were 11 tropical cyclones, including depressions, storms and hurricanes, he said.

Also during an El Nino, he said, “;during our wet season, especially after December, we experience very dry conditions.”;

This is troubling because many parts of the state have been dry in the past few months, he said.

But he had good news for surfers. Usually in El Nino years, more high surf occurs on the North Shore as storm systems push closer to Hawaii in the winter, he said.

El Nino is expected to continue through the winter and into next year, NOAA said in a report yesterday on its Web site.

El Ninos normally last about a year and have wide-ranging impacts. In the past they have caused damaging winter storms in California, more storms across the southern United States, severe flooding and mudslides in Central and South America, and drought in Indonesia, NOAA said.