There’s still six weeks to go, but the 2015 Central Pacific hurricane season is already one for the record books.
Fueled by a strong El Nino weather pattern and warmer waters in general, the ocean around the islands has seen more hurricanes and more named tropical storms than any time in recorded history.
What’s more, the Central Pacific has experienced some notable firsts, including the formation of three named cyclones in a remarkable four-day period in July and a pair of major hurricanes spinning at the same time in late August.
The Aug. 29 satellite image that went viral showing three massive storms all churning east of the international date line — another meteorological first — made Hawaii look small and vulnerable.
Oddly enough, last year’s hurricane season punched the islands with significantly more power, as the Big Island endured a direct hit from Tropical Storm Iselle, causing many millions of dollars in damage, while the rest of the island chain felt the indirect and damaging effects of two other tropical cyclones.
This year?
So far none of the main Hawaiian Islands has been under a tropical storm warning (stormy conditions expected within 24 hours), according to the National Weather Service. Oahu and Kauai haven’t even been under the lesser tropical storm watch (possible storm conditions within 36 hours).
“We’ve been really lucky,” said Robert Ballard, science and operations officer with the Central Pacific Hurricane Center in Honolulu. “Several systems have already gotten uncomfortably close, and we can consider ourselves very, very lucky if we get through the rest of the season unscathed.”
With a month and a half left in the June 1-through-Nov. 30 hurricane season, there is plenty of time for more storms to find their way into our neighborhood of the Pacific.
Hopefully the worst won’t be left for last, like in late November 1982, when Hurricane Iwa blasted Kauai and Oahu, causing more than $300 million in damage.
That year was a strong El Nino year, too.
“It only takes one,” Ballard said of the late-season possibilities.
As a matter of fact, that one could be Hurricane Olaf, which is expected to move across 140 degrees longitude, the eastern edge of the Central Pacific, on Tuesday.
If it does cross over, Olaf will become the 15th tropical cyclone in our region this year, further smashing the previous record of 11 set in both 1994 and 1992.
Central Pacific weather records go back as far as 1949.
So far new records for the Central Pacific also include the number of hurricanes — seven (the previous record was five in 1994); tropical storms — six (tied with 1982); named storms — 13 (previous record 10 in 1992 and 1994); and named storms formed in the Central Pacific — eight (previous record four in 1982).
Forecasters knew it was going to be a busy year when three storms — Ela, Halola and Iune — materialized between July 8 and 11.
While none of the storms threatened the islands, they were the earliest three cyclones to form in the Central Pacific in recorded history. The previous record belonged to Wali on July 17, 2014.
Another notable first occurred in late August when three major hurricanes — Kilo, Ignacio and Jimena — were spiraling at the same time in the central and eastern Pacific Ocean.
It was the first time three Category 4 storms with winds in excess of 110 mph occurred simultaneously in any ocean basin, National Weather Service officials said.
It was also the first time hurricane watchers tracked two major hurricanes — Kilo and Ignacio — in the Central Pacific at the same time. Up to this point, not even two Category 3 hurricanes, let alone two Category 4s, had existed in the Central Pacific simultaneously, officials said.
The Central Pacific averages four to five tropical cyclones a year. With El Nino in the forecast, National Weather Service officials predicted five to eight storms.
Now, however, we’re looking at a possible 15th storm and maybe more.
How did we get to this point?
Phil Klotzbach, a hurricane researcher with Colorado State University, said the Central Pacific is ordinarily considered a marginal basin for tropical storm formation and intensification.
Klotzbach said the middle of the Pacific usually displays strong vertical wind shear, that high-altitude change in wind direction that acts to weaken tropical storms.
But this year, he said, El Nino helped to drastically reduce vertical wind shear, making the basin much more vulnerable to cyclones.
Klotzbach said El Nino also helped to create warmer sea surface temperatures in the tropical Pacific, a condition that fuels cyclone formation.
But Axel Timmermann, a University of Hawaii oceanography professor, said not all of the warming around Hawaii can be blamed on El Nino.
The warming trend, he said, is actually part of a large-scale pattern that extends all the way up to Alaska and California going back to November 2013.
Timmermann said it looks like the atmospheric response to El Nino in 2015 helped to maintain and intensify this boomerang-shaped Northeast Pacific pattern. Along with the extended warming came a drop in tradewinds, further heating up the ocean surface, he said.
In addition, there’s a suspicion the boomerang pattern feeds the development of El Nino — “a double-whammy situation” in the Pacific, he said.
“With El Nino in the equator and the boomerang pattern of the Northeastern Pacific warming, both provide a nice breeding ground for hurricane development,” Timmermann said in an email. “The hurricane season is not over yet.”
Klotzbach said there’s another intensity metric used to measure tropical cyclone activity. Accumulated cyclone energy, or ACE, combines intensity, frequency and duration of storms into one number.
This year’s Central Pacific hurricane season still trails 1994 for the basin’s highest ACE unit number — 107 units to 100, he said. But with nearly six weeks left in the hurricane season, he said, there’s a real possibility 2015 will eclipse the 1994 record.
To compare, last year’s Central Pacific ACE score was only about 40, while the Atlantic typically generates about 100 ACE units in an average season.
Ballard said wind shear has actually picked up over the latter half of the hurricane season, which has helped to keep the islands safe.
“Unfortunately, we can’t bank on that to protect us,” he said.
Ballard urged Hawaii residents to stay aware and be prepared because more storms may be on the way, and wind shear might not always be there to fight them off.
Considering how strong El Nino is this year, he said, the hurricane season could stretch well beyond November.
“You better be ready,” Ballard said.
