KAILUA-KONA — The Big Island can expect below-average rainfall this winter as El Nino sets in, but the state’s southernmost land mass should escape drought conditions until spring.
“The good news is that it’s expected to be a weak El Nino,” said Honolulu-based National Weather Service Senior Hydrologist Kevin Kodama. “With weak events, you can still have some rain events squeak through.”
El Nino has a 70 to 75 percent chance of developing within the next couple months, and it’s likely to persist until spring, the National Weather Service said Friday. During an El Nino event, sea surface temperatures become warmer than normal, disrupting easterly trades and resulting in drier weather for Hawaii.
The drier conditions could impact farming and water catchment systems. But, farmers should not expect effects like occurred a decade ago when moderate El Nino conditions set in, parching the island and damaging crops like Kona coffee and causing livestock deaths islandwide, said Kodama.
“The expectation is that it’s not going to be a super bad, statewide drought like we had in 2009-10, which was really bad for the Kona side,” he said. That year, the service received reports that any non-irrigated coffee trees in the region were dying amid drought levels reaching the most intense level, “exceptional.”
The National Weather Service in Honolulu released its annual wet season rainfall outlook on Friday, pointing to a reduction in precipitation coming out of the second wettest dry season during the past 30 years in Hawaii.
Statewide, most locations saw above-average rainfall during the dry season, which runs May to September. Just one area of the state, the mauka Kona Coffee Belt region, typically sees its wet season during those months, and this year, rainfall for the area was near or below average, Kodama said.
Drought did develop in Maui County and leeward areas of the Big Island and Oahu, reaching “severe” levels in some areas, before tropical cyclone activity brought record-breaking wet conditions to the state.
“When August rolled around, especially starting with Lane and continuing all the way through much of September, it was very wet across the state, especially windward Big Island areas that got hit hard by Lane,” Kodama said.
While some of the rain did make it to leeward areas, parts of Kona and Kohala were left dry, however.
“In some spots, it was wet, but places like Kainaliu and Kealakekua are both at 60 percent of average for May to September,” Kodama said. “The Kona slopes are one of the few areas on the Big Island that didn’t hit above-average or completely at or near-average levels.”
Though Kona and other leeward areas may not have received as much rainfall, drought was considered eliminated statewide as of October, according to the service.
Just a dab of abnormally dry area persisted on the leeward sides of the Big Island and Maui, according to the most recent U.S. Drought Monitor report issued on Thursday.
Kodama said Friday the remaining abnormally dry areas will likely disappear in the coming weeks thanks to rainfall and the likelihood that El Nino conditions won’t take hold until the last month of the year.
As of press time Friday, a flash flood watch was posted for the state as unstable and moist conditions are forecast to fuel afternoon and evening showers and thunderstorms. Up to 2 inches of rain could fall.
“The early part (of the winter dry season) might be decently wet,” said Kodama. “But, once we hit December (when the El Nino is expected to take hold) and then on through the February-March time frame, we’re going to be below average in terms of rainfall.”
That decline in rainfall is expected to persist through April, he said. Drought could set in by the end of February, and by March, some lower leeward slopes might see “severe drought” conditions develop.
“We’re not expecting it to be that bad this coming wet season, but we are expecting below average rainfall,” said Kodama.
Impacts from drought will likely be seen first in the agricultural sector, starting with parched pastures before spreading to other commodities like ornamentals and fruits, said Kodama.
“The Ag sector in Hawaii is kind of like the canary in the coal mine, they get hit first with drought,” he explained.