LIHUE — It’s been 10 years since a hurricane season in the Central Pacific was this quiet.
That’s according to the National Weather Service, which released the 2017 hurricane season summary last week.
NWS tallied just two cyclones throughout the whole season — something that hasn’t happened in the Central Pacific since 2007. Predictions were five to eight cyclones for the 2017 season, which ran from June 1 to Nov. 30.
Both storms entered into the region in late July, which is right around the peak in the season, according to John Bravender, NWS warning coordination meteorologist.
“There wouldn’t be anything unusual about the two that formed in July. The unusual part is how the season shut down after that,” he said.
Bravender continued: “We had this big debate going on in the outlook, whether it was going to stay neutral or go to El Nino. (Instead) we went to La Nina waters and after July, it was clear.”
In May, the National Oceanic and Atmospheric Administration predicted a 40 percent chance of near-normal or above-average tropical cyclone activity and a 20 percent chance of below-normal activity.
Tropical Storm Fernanda formed July 20-22 and sustained maximum wind speeds of 50 miles per hour. Tropical Storm Greg turned into a depression by the time it entered the Pacific region and sustained maximum wind speeds of 35 mph. That’s compared to Hurricane Iniki’s 1992 arrival, with wind speeds of 145 mph.
“Fernanda and Greg were short-lived and they weakened before they approached,” Bravender said. “They were far enough north that the water was cooler and we had a lot of wind shear. That helps weaken them.”
The 2016 hurricane season saw seven tropical cyclones; in 2015, 16 made an appearance in the Central Pacific. There were five in 2014, six in 2013 and a streak of three years between 2010 and 2012 where one cyclone crossed into the region each year.
Lately, even in the quieter years, Hawaii has spent more time in the crosshairs of a hurricane than in 2017.
“Last year with seven, half of those were threats to the state,” Bravender said. “We had Darby, Madeline and Lester.”
The reason for the strange change in character for the 2017 hurricane season after July is still being studied and theories are being formed. Currently, scientists are looking to large-scale trends for answers.
Bravender said regardless, this season’s uptick in trade winds had a hand in part of it. The rest is still being studied.
“We know El Nino and La Nina impact things on a seasonal and multi-year scale, and there’s also smaller scale influences on the order of months,” Bravender said. “Predicting development is still something that we’re working on.”