El Nino is gearing up to be one for the record books.
Scientists say the recurring phenomenon that has helped heat up the Pacific Ocean and fuel hurricanes is the strongest since the landmark El Nino of 1997-98.
Long before El Nino’s normal peak around the end of the year, Hawaii has already been feeling the effects, with increased sea temperatures contributing to stifling heat waves. Sea temperatures are around three degrees above normal in the central equatorial Pacific, with temperatures from June through August ranking the third highest since record keeping began in 1950, behind only the mega-El Ninos of 1987 and 1997.
Trade winds have also been persistently weak and even reversed across the basin — and not just around Hawaii when tropical storms pass to the north and cut off the flow of the trades.
El Nino has played a big role in this summer’s sweltering heat, said Axel Timmermann an oceanographer and El Nino researcher with the International Pacific Research Center in Honolulu. But high temperatures have also been caused by warming in the North Pacific that began last year and is an anomaly.
“That contributed to weaker summer trade winds, higher atmospheric humidity and the uncomfortable conditions that we have experienced now for several months,” Timmermann said.
Climate models used by the Australian Government Bureau of Meteorology predict El Nino will just keep strengthening over the next few months, then persisting on a weakening trend into the autumn of 2016. The NOAA Climate Prediction Center has a slightly more conservative forecast for how long El Nino will last, with the end stages pegged for springtime next year. Scientists have already sounded the alarm on potential massive coral bleaching in Hawaii because of the warmer water, saying the damage could be the worst the state has seen yet.
El Nino has fueled a massive Eastern and Central Pacific hurricane season as well. More activity could still be coming, with warmer sea temperatures having the potential to prolong the season, Phil Klotzbach, a hurricane expert at Colorado State University, told West Hawaii Today. The Eastern Pacific has had twice the accumulated cyclone energy for the month of October during El Nino years compared with neutral years, in data comparisons that go back to 1988.
The Central and Eastern Pacific have already been host to three Category 4 hurricanes spinning at once — Kilo, Ignacio and Jimena, the first time that has ever been recorded in any ocean basin, according to Tom DiLiberto, a meteorologist with the NOAA Operational Prediction Branch.
Looking ahead, Hawaii can expect a wetter than normal October and November, with potential for more humidity, Timmerman said, then a drying out and return to drought from December to March.
A shifting northward of a subtropical jet stream in wintertime typically brings rain away from Hawaii and into California, Klotzbach said.