HILO — A subtropical cyclone passing by Hawaii last weekend closed out what National Weather Service described as an “erratic” wet season.
The cyclone, better known as a Kona (or leeward) low, brought nearly 4 inches of rain to parts of East Hawaii. The entire island has experienced lower than usual rainfall this season.
Kona lows typically bring 20 inches of rain or more.
“Usually, when you get Kona lows they produce a lot of rain,” National Weather Service hydrologist Kevin Kodama said Thursday. “But the way it worked out, they kind of under-performed (last weekend). Usually, they end up being much, much bigger events.”
“The weekend was a little wet, but the worst rainfall was around 40 miles to 100 miles east of the Big Island, in our offshore waters,” Kodama said.
A Kona low also passed by in December. It’s more common for them to occur at that time of year. Less than 10 percent of all Kona lows take place in April and May.
“The interesting part has been that we haven’t really seen a good one since 2008,” Kodama said.
Aside from the last week’s Kona low, rain gauges around the island posted lower than average rainfall totals in April, continuing a months-long trend.
At Puuanahulu, 1.02 inches of rainfall, or just 39 percent of the average, was recorded for April, Kona International Airport saw 1.36 inches of rainfall, or 84 percent of the monthly average, and South Point saw 1.87 inches, or 78 percent of the monthly average. The three gauages in Waimea all registered between 50-60 percent of average.
The highest monthly total was recorded at Kawainui Stream: 15.33 inches, which is 99 percent of average.
“We’re still in droughts on the Big Island,” Kodama said. Hawaii Island is the last area in the state still under drought: parts of North Kona, South Kona and Ka‘u are listed as being in “severe” drought according to the U.S. Drought Monitor map. Other leeward areas are under “moderate” drought.
The Kona low brought considerable rainfall to the leeward side of the island, but Kodama said the because the weather event was so recent, it was too early to tell if it was enough to pull out of drought.
Leeward areas seeing above-average rainfall included Kealakekua (9.85 inches, or 225 percent above average); Honuanu (5.83 inches, or 133 percent; Waiaha (5.99 inches, or 149 percent above average; and Kainaliu (7.58 inches, 178 percent above average).
“We’ll see what the farmers say,” he said.
Despite the low rain totals on Hawaii Island, the 2016-17 wet season itself was ranked 15th of the past 30.
“Right in the middle,” Kodama said. Overall, “It’s been really up and down…when you go dry-wet-dry-wet it, that averages out.”
Compared with other islands, the Big Island has received lower rainfall totals overall. Weather systems in February and March that brought flash flooding to Oahu and Kauai dissipated as they moved south.
Kodama said that climate forecasters were expecting above average temperatures this summer because water temperatures are currently warmer than usual. This would also bring more humidity, he said.
Email Ivy Ashe at iashe@hawaiitribune-herald.com.