On the 25th anniversary of the season that brought devastating Hurricane Iniki to the islands, National Weather Service forecasters are warning of another possible busy hurricane season.
The Central Pacific Hurricane Center on Wednesday predicted five to eight tropical cyclones for the 2017 hurricane season from June through November.
With mixed signals regarding the potential for an El Nino forming, forecasters said climate conditions suggest a near- to above-normal season across the Central Pacific basin.
The seasonal outlook, they said, calls for a 40 percent chance of an above-normal season, a 40 percent chance of a near-normal season and a 20 percent chance of a below-normal season.
An average Central Pacific season sees four to five tropical cyclones, which include tropical depressions, tropical storms and hurricanes.
In a news conference Wednesday at the Hawaii Emergency Management Agency’s Diamond Head headquarters, National Weather Service officials also offered their forecast for the upcoming dry season, saying conditions favor above-normal rainfall during the first half of the summer.
But while wet conditions are expected to affect windward areas and Kona on Hawaii island, most leeward areas are likely to be seasonably dry, with the probable spreading of existing drought and the development of new drought areas, Weather Service hydrologist Kevin Kodama said.
El Nino a key factor
Wednesday’s Central Pacific hurricane season outlook was largely based on data from the National Oceanic and Atmospheric Administration’s Climate Prediction Center, which is forecasting the possible development of a weak El Nino, along with the potential for weaker-than-average vertical wind shear.
El Nino, the global weather pattern triggered by warming water at the Pacific’s equator, decreases upper-level wind shear over the tropical Central Pacific, which favors the formation of more and stronger tropical cyclones.
The last time the islands were affected by El Nino was in 2015 when 14 named storms, including eight hurricanes — five of which grew into major hurricanes — wandered into the Central Pacific. Extreme El Nino conditions helped generate the most active season since reliable record keeping began in 1971.
Last year saw a weak La Nina episode — El Nino’s polar opposite. But the Central Pacific still witnessed an above-average hurricane season with six tropical cyclones, probably due to what scientists described as a phenomenon involving residual warm water left over from El Nino.
While key indicators last month were favoring El Nino formation, conditions now indicate a neutral position, with models split on whether El Nino will materialize, officials said.
The National Weather Service hasn’t issued its forecast for the Eastern Pacific hurricane season yet, but a private service, AccuWeather, recently predicted an above-normal number of tropical storms and hurricanes. According to AccuWeather, warm ocean waters could produce 19 tropical storms, 10 hurricanes and seven major hurricanes.
Plenty of powerful storms have traveled from the Eastern Pacific to the Central Pacific to threaten Hawaii. Tropical Storm Iselle, which slammed into the Big Island in 2014 and caused tens of millions of dollars in damage, is an example. So is Tropical Storm Darby, which crossed Hawaii island near Pahala on July 23 before pounding Honolulu with heavy rain that caused flash flooding.
Hurricane Iniki, the most powerful storm to make landfall in Hawaii, formed in the Central Pacific before walloping Kauai on Sept. 11, 1992. Damage to Kauai, and to a lesser extent Oahu, added up to more than $3 billion in 2017 dollars.
Threat to isles unclear
Chris Brenchley, Central Pacific Hurricane Center director, said the season’s Central Pacific outlook doesn’t specifically predict how many tropical storms will threaten the islands.
“There are years when we have a lot of activity, and those storms avoid the state,” Brenchley said. “We could have a year where we have one singular tropical cyclone that directly impacts the state. So the takeaway message is: It doesn’t matter how many. It matters where those cyclones ultimately end up.”
Brenchley said this hurricane season may be the fifth straight year in which the Central Pacific average of four to five tropical storms will be exceeded.
He said the Central Pacific basin may be transitioning to a new period of greater tropical cyclone activity in response to changes in global sea surface temperature patterns that last from 25 to 40 years.
Preparedness urged
Officials urged residents to start preparing and thinking about what will happen when a hurricane strikes.
Hawaii Emergency Management Agency Administrator Vern Miyagi said his agency is now urging residents to prepare an emergency kit with 14 days of food and supplies rather than the previously recommended seven days.
Based on research and the experience of other states, it will take extra time to re-establish power plants, harbors and other key facilities following an especially big storm, Miyagi said.
“If our public is resilient and if they can take care of themselves for that 14-day period, it gives us a chance to get that critical infrastructure back up,” he said.
Now is the time to put your emergency plan together, he emphasized.
