Dry weather comes to 40% of the isles

Emerging from the wettest dry season in 30 years, Hawaii is already slipping into the drought that was predicted for this winter under the spell of one of the strongest El Nino events ever recorded.

More than 40 percent of the main islands are now experiencing “abnormal drought,” according to the latest U.S. Drought Monitor update, issued Thursday by the National Drought Mitigation Center.

So far, leeward regions are the most affected. Places such as Honolulu Airport received only 9 percent of normal December rainfall while Lihue Airport saw only 29 percent, according to the National Weather Service.

While Hilo and some other windward locales continued to be buffeted by strong, moisture-laden tradewinds in December, look for drier weather ahead across the archipelago.

In a paper published last month, University of Hawaii researchers ran a National Oceanic and Atmospheric Administration computer model 40 times with slightly different variables, and each time the predicted outcome called for below-normal winter rainfall.

Most of the model predictions offered forecasts from 1 inch to 1.5 inches below normal from December through February.

H. Annamalai, a senior researcher with UH’s International Pacific Research Center and lead author of the East-West Center Asia Pacific Issues analysis, said his team was surprised by the unanimous consensus of the computer predictions, but added that it only goes to show the strength of the current El Nino.

As a matter of fact, Hawaii’s burgeoning dry spell is part of a larger El Nino- triggered drought dogging islands across the Pacific.

“Most parts of the South Pacific islands have been experiencing droughtlike conditions since the summer of 2015 and are expected to face the persistence of drought for two more seasons (winter and spring),” Annamalai said.

Annamalai’s paper, co-authored by UH colleagues Victoria Keener, Matthew J. Widlansky and Jan Hafner, describes an extended and strengthening El Nino drought that began in the southwestern Pacific, bringing famine to Papua New Guinea and Vanuatu, and moving eastward to Hawaii.

With an estimated 4.7 million people potentially affected, the prolonged drought could compromise freshwater and food supplies across the Pacific and affect public health, economies and food distribution, and even cause civil unrest, the paper said.

The UH analysis, titled “El Nino Strengthens in the Pacific: Preparing for the Impacts of Drought,” suggests strategies that island governments and aid groups can take to help deal with the powerful climate phenomenon.

Hawaii, meanwhile, is probably in a better place than other Pacific islands thanks to an extreme, El Nino-driven wet summer, Annamalai said.

National Weather Service officials reported that Hawaii’s 2015 dry season, from May through September, was the wettest in 30 years. August and September were the wettest on record for many locations, while some monthly totals were more than double previous records.

Lots of that moisture came from a record number of El Nino-triggered cyclones that plied the Central Pacific in 2015, as well as from El Nino-fueled warmer-than-normal waters that surrounded the islands.

The Aloha State was declared drought-free by the U.S. Drought Monitor on Oct. 6 for the first time in 7-1/2 years. But that lasted only five weeks before dry conditions started to color a small portion of the the monitor’s online map of the islands.

Hawaii’s area of “abnormal drought” — the monitor’s least severe stage of drought — has now grown to 42.5 percent of the islands, all on the leeward sides of the state’s four largest islands: Hawaii, Maui, Kauai and Oahu.

The largest stretch of drought area is found on Hawaii island, with more than 50 percent of the island — covering almost all of the west side — affected.

“Most stations (across the islands) were below normal for December,” said Chris Brenchley, meteorologist with the National Weather Service office in Honolulu. “It will tend to continue to be dry, and the impacts of the drought will build over time.”

That’s not to say there will be no rainstorms, Brenchley said. As usual, windward areas will continue to get more rain than leeward areas. The difference is there will be fewer big soakers, he said.

Scientists and forecasters have been predicting winter drought here for months. And with such a strong El Nino, the dry spell could stretch throughout the spring and maybe into summer, they say.

Weather service hydrologist Kevin Kodama previously predicted the islands would see widespread “moderate drought” with embedded areas of “severe drought” by the end of April. Isolated “extreme drought” is also a possibility, he said.

In addition, he said, look for leeward pastures to degrade and water supply catchment systems to start running low, plus an earlier start to the 2016 fire season, as parched landscapes fade to brown.