A wet start to the dry season in East Hawaii – West Hawaii Today

June 1 marked the official start of the dry season for most of Hawaii, but that might not be apparent after the rainfall East Hawaii has received so far this month.

Hilo International Airport as of 8 a.m. Tuesday had recorded 4.13 inches of rain for the month.

That would translate to 13.77 inches for the month, almost twice the normal June precipitation, if the rainfall rate continues for the remainder of the month.

The airport’s total, however, pales in comparison to the rain that found its way to most of the windward gauges on the Big Island.

North of Hilo, Laupahoehoe received 12.24 inches and Hakalau had 12.67 inches so far this month. Glenwood, south of Hilo in the upper Puna rainforest, reported 10.94 inches, while Pahala, in the heart of Ka‘u coffee country, tallied 8.4 inches since June 1.

All of those totals are well above the norm — especially Hakalau, with a total almost five times that of an entire average June, and Pahala, which already has received more than four times its usual June rainfall.

“It’s not a switch like a light switch. It doesn’t just become dry” at the start of the dry season, said hydrologist Tina Stall of the National Weather Service’s Honolulu forecast office.

In fact, drought conditions that have gripped much of the Big Island the past five years, spurred by El Nino — warmer than normal equatorial waters in the Pacific Ocean — are gone, although there are locations on the Big Island still considered abnormally dry.

A pair of Kona low storms brought deluges that caused flooding and damage in March, but the spate of recent rainfall in East Hawaii is unrelated, according to Stall.

“We’ve had pretty typical trade wind weather for the past several weeks. There are just certain embedded areas of higher moisture that come through there,” she said. “I wouldn’t attribute it to climate.”

According to Stall, Hawaii remains in neutral conditions, neither El Nino or its opposite, La Nina, “but we’re trending toward El Nino.”

Stall said typical El Nino years in Hawaii bring “above normal precipitation” during the dry season.

“That’s partly due to the tendency for more tropical cyclones in the Central Pacific during an El Nino year,” she explained.

Hurricane season started June 1 and runs through Nov. 30. Forecasters have predicted a busy season in the Central Pacific with five to 13 tropical cyclones.

The National Oceanic and Atmospheric Association’s Climate Prediction Center last month forecast that an El Nino cycle had an 82% chance of occurring between now and July and a 96% chance of continuing through December to February.

“With an El Nino, the dry conditions really don’t set in until the winter, so if we end up getting above normal precipitation in the dry season, we could delay the effects of drought a little more. But this winter, it’s going to likely dry out,” Stall said.

El Nino doesn’t guarantee the development of tropical cyclones — which include hurricanes, tropical storms and tropical depressions — but does increase the odds they’ll occur. And the forecast of five to 13 cyclones in the waters around Hawaii isn’t a prediction of landfall by any of the potential storms, although that could happen.

Most tropical cyclones enter the Central Pacific basin — which stretches from 140 degrees longitude north in the east and the International Date Line in the west — from the Eastern Pacific.

No tropical cyclones have either entered or formed in the Central Pacific so far this year, but at least three have developed in the Eastern Pacific so far this month. Tropical storms Amanda and Boris have dissipated and Tropical Storm Cristina was bringing heavy rain along the Central American coast and is expected to drift westward but weaken without entering the Central Pacific.

West Hawaii, and the Kona coffee belt in particular, experiences its wet season in the summer, unlike most of Hawaii. So far, leeward Big Island rain gauges haven’t shared in the June rainfall bounty.

Ellison Onizuka Kona International Airport in Keahole had received just a trace of rain this month as of 8 a.m. Tuesday. And the coffee belt gauges in Waiaha, Kealakekua and Honaunau reported 0.68 inches, 0.28 inches and 0.13 inches, respectively.

Asked if Kona coffee growers will receive their expected summer rainfall, Stall replied, “It’s too early to tell at this point, but I don’t have reason to think otherwise.”

Email John Burnett at john.burnett@hawaiitribune-herald.com.