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Hawaii hasn’t been threatened by a major tropical cyclone since 2009 — and with the 2012 hurricane season set to officially wrap up Friday, it’s safe to say it was another quiet year.
"We thought it might be a little bit of a below-normal season, but it ended up being even weaker than that," said Robert Ballard, science and operations officer for the Central Pacific Hurricane Center in Honolulu.
Forecasters in May predicted two to four tropical cyclones would enter the Central Pacific this season, but only one did. Hurricane Daniel popped up in the Pacific in early July and died out far to the southeast of the Hawaiian Islands soon after entering the Central Pacific.
Ballard said 2012 saw fewer storms than estimated because an expected switch to an El Niño weather pattern from a La Niña weather pattern didn’t pan out.
"What that essentially means is that we don’t have either La Niña, which is cooler than normal sea surface temperatures, or El Niño, which is warmer than normal sea temperatures," he said. What’s happening instead is called ENSO neutral, which is characterized by near-average sea surface temperatures. ("ENSO" stands for El Niño/Southern Oscillation.)
If the switch had occurred as predicted in mid- to late summer, water in the eastern Pacific Ocean would have warmed up, creating more favorable conditions for storms to develop. Hawaii’s worst hurricane on record, Hurricane Iniki in 1992, occurred during an El Niño weather pattern.
"Typically the weather goes in cycles, and cycles can take a few years to go one way," Ballard said. "We don’t completely always understand those cycles. … We think we’re getting better but there’s always more to learn."
Ballard said ENSO neutral is expected to continue through the winter months, and it could make December, January and February wetter than normal.
LAST YEAR also yielded only one storm in the Central Pacific, and 2010 resulted in no storms for the first time since 1979. An average hurricane season in the Central Pacific, which includes Hawaii, has four to five cyclones, according to the National Weather Service. A cyclone can be a tropical depression, tropical storm or hurricane.
Ballard said having a few slow storm years is not uncommon, but "maybe not quite as dead as the last couple years."
"That’s pretty unusual," he said.
According to National Weather Service data, the only other three-year period since 1966 that comes close to mirroring what’s going on in the ocean now is when no tropical cyclones passed through in 1979, followed by two each in 1980 and 1981.
"This is a pretty similar quiet period to what we saw before things got busy for us in 1982," Ballard said, refering to the year Hurricane Iwa hit the isles.
"It would certainly be unprecedented if we had another superquiet year as the last year has been," he added. "Statistics suggest it should be busier, but Mother Nature doesn’t always follow statistics."
Even though a major hurricane hasn’t hit the isles since Iniki in 1992, Ballard said several cyclones have posed serious threats to parts of the state since then. He cited Fernanda in 1993, Daniel in 2000, Jimena in 2003, Flossie in 2007 and Felicia and Neki in 2009.
"All of these systems got close enough to the islands for us to be very, very concerned," Ballard said. "So you could say we’ve been pretty lucky, actually."
Hawaii tends to be lucky because the islands are flanked on the east by cool water that robs storm systems of their energy, and because strong upper-level winds are aloft during most of hurricane season, which runs from June 1 to Nov. 30.
"Those strong winds aloft are not helpful for hurricanes," Ballard said. "But if the strong winds aloft are absent, which happens a little later in the season usually, and the waters are a little warmer … that’s usually when the islands are at their greatest threat."
Ballard said it’s too soon to tell what could happen during the 2013 season, and he cautioned that yearly storm predictions aren’t at all indicative of what, if anything, might happen in the islands.
"Whenever we make those forecasts, we’re definitely not making a forecast for Hawaii," Ballard said. "We can’t tell you whether or not Hawaii is going to be hit."
And just because Hawaii has gone two decades without being severely affected by a hurricane, that doesn’t mean it isn’t vulnerable.
"It’s important to let people know that even thought we’ve gone through a long period of not much hurricane activity in Hawaii … we’re still in the hurricane belt," Ballard said.
"It’s still very likely that at some point the Hawaiian Islands will get hit again."
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