As the strong El Nino weather pattern continues to weaken, National Weather Service officials admit being a little less certain about what to expect this hurricane season but nevertheless predict four to seven tropical cyclones from June to November.
Central Pacific Hurricane Center forecasters Thursday said to expect anywhere from an average to an above-average hurricane season, with an outlook that calls for an equal 40 percent chance of either a normal or above-normal season and a 20 percent chance of a below-normal season.
An average Central Pacific hurricane season sees four to five tropical depressions, tropical storms or hurricanes.
“There are conflicting signals for the upcoming season, giving us a little more uncertainty in what 2016 has in store for us,” said Chris Brenchley, warning coordination meteorologist with the Central Pacific Hurricane Center.
Last year’s monster El Nino helped to generate 15 tropical cyclones — eight of them hurricanes — in the Central Pacific, making 2015 the most active season since reliable record keeping began in 1971.
Brenchley, speaking at a Honolulu news conference, said this year’s outlook is based on the expectation that El Nino conditions will be transitioning to La Nina during the hurricane season. La Nina, he said, typically suppresses hurricane activity in the Pacific by increasing wind shear and causing an irregular sinking motion in the atmosphere.
However, the Central Pacific basin might be shifting toward a more active cycle in response to changing global sea surface temperature patterns, he said.
Brenchley said these conflicting climate indicators, along with model predictions for weaker vertical wind shear and warmer ocean waters, suggest that the hurricane season will likely be normal or above normal.
State climatologist Pao-Shin Chu predicted an above-average hurricane season last month, citing 2014 research by University of Hawaii colleagues that demonstrated how residual subsurface El Nino-generated heat is likely to drift into the eastern Pacific in the summer, leading to a greater chance of hurricane genesis there.
Chu, a UH meteorology professor, said Thursday that he stands by his prediction because of current indications of heat in the equatorial and eastern Pacific.
If conditions in the ocean off Mexico do become ideal for tropical storm formation, Hawaii will have to be wary of storms heading westward from that area.
Tropical Storm Iselle, which crippled parts of Hawaii island in 2014, and many other powerful cyclones that threatened the islands, including hurricanes Guillermo, Hilda, Ignacio and Jimena last year, are examples of storms that originated from that area.
Active hurricane season or not, officials Thursday urged Hawaii residents to be fully prepared before the hurricane season.
“After last year many of us felt like we had prepared enough. We were expert at preparing,” Brenchley said. “The fact of the matter is there’s always more you can do. My project list: windows. I’ve got to get my jalousie windows fixed up. The termite-ridden front door is always a good one to check on as well.”
Dennis Hwang, co-author of the “Homeowner’s Handbook to Prepare for Natural Hazards,” said that while the hurricane season starts in June, the active part usually gets going in July, so the time to prepare is now.
Hwang, a coastal hazard mitigation specialist with the UH Sea Grant program, suggested taking two or three weekends to make sure your house is in good condition, including installing hurricane clips on homes built before 1988.
“You can do your emergency supplies a week before (a storm),” he said. “But if you wait for a (hurricane) watch or warning, everything is going to be gone. Normally I have my emergency supplies prepared all year round.”
Also important, he said, is an evacuation plan, as well as planning for where your family is going to stay during a storm — in a shelter or at home.
During Thursday’s news conference the National Weather Service also presented its climate outlook for the 2016 dry season from May through September.
The Climate Prediction Center is forecasting above-normal rainfall during the latter half of the season, said Kevin Kodama, National Weather Service senior hydrologist.
Kodama said wet conditions will mainly affect windward slopes and possibly the slopes of Kona on Hawaii island, which is the only leeward area in the state that usually sees a wet summer.
The news is not so good for most leeward areas across the island chain. Kodama said he expects the current drought to expand into new areas.
As a result, this year’s exceptionally active brush fire season is expected to worsen, he said, noting that burned acreage in 2016 already is more than double the 2015 total.
As for the 2015-2016 wet season, powerful El Nino conditions helped to make it Hawaii’s fifth-driest October-to-April wet season over the past 30 years, Kodama said.
While weak cold fronts brought localized wet conditions to many north-facing slopes, he said, most leeward areas saw less than
50 percent of average rainfall, leaving the landscape parched.