Rainy season begins with a dry October

  • KODAMA

Although the long-term forecast is for a wetter-than-average rainy season for most of Hawaii, much of the Big Island, especially East Hawaii, had a drier-than-usual October.

“Due to the lack of trade winds, windward Big Island rainfall totals for October were mostly below 50% of average,” said Kevin Kodama, senior hydrologist for the National Weather Service in Honolulu.

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Hilo International Airport received 4.82 inches of rain, 49% of its average October rainfall of 9.77 inches.

Even areas that are normally extremely wet, such as Glenwood, in Puna’s upslope rain forest, measured less than 5 inches during October. Glenwood’s total of 4.91 inches is just 28% of its October norm of 17.25 inches.

At 88.25 inches through Oct. 31, the Hilo airport is 11.4 inches below its year-to-date norm, while Glenwood’s 135 inches for the year is just 71% of its yearly average through October.

October was positively parched in Honokaa. The former sugar plantation town tallied just 0.86 inches of rain for the month, less than a fifth of its October average.

Drought persists on much of the Big Island, with the U.S. Department of Agriculture having declared Hawaii and Maui counties as primary disaster areas in March, which allows the Farm Service Agency to extend emergency credit to agricultural producers affected by drought conditions.

“A state agriculture extension service report indicated poor pasture conditions in several areas,” Kodama said in his Oct. 8 drought information station. “In the leeward Kohala area, forage production was down by at least 30%. Forage production was also significantly below normal in portions of the Ka‘u District. Pastures in parts of the Hamakua District were also extremely dry.”

The Kamuela Upper, Piihonua and Waiakea Uka rain gauges all set records for their lowest October rainfall totals, and the Mountain View gauge recorded its lowest October total since 2003.

During the weather service’s annual wet season outlook on Oct. 16, Kodama predicted rainfall will gradually pick up this month, with “wetter-than-average conditions in the large scale starting in December and then continuing through April.”

“The strength of the La Nina can affect what the rainfall distribution will be during the wet season,” he said.

La Nina conditions — which means cooler-than-normal ocean temperatures near the equator — are likely to continue through spring.

Kodama said the La Nina also contributed to a relatively quiet tropical cyclone season in the Central Pacific. Hurricane season is over at the end of this month.

Ellison Onizuka Kona International Airport recorded a total of just 0.13 inches of rain for October, 10% of normal. Meanwhile, many sites along the Kona slopes and in the Pohakuloa region had near-to-above average monthly rainfall totals.

Three of the four Kona coffee belt gauges, Waiaha, Kainaliu and Honaunau — which experience their rainy season in the summer — received more than 70% of their October average. The fourth, Kealakekua, had the most rainfall at 4.64 inches, slightly more than its usual October average.

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All four coffee belt gauges have recorded higher-than-average totals for the year.

Email John Burnett at jburnett@hawaiitribune-herald.com.

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