Half a month’s worth of rain dumped in one day in Hawaii

Heavy rainfall across the Hawaiian Islands on Monday destroyed homes, overflowed the Kaupakalua Dam, and inundated roadways as some areas received up to nearly half a month’s worth of rain in a single day.

Residents of Haiku, Hawaii, were ordered to evacuate on March 8, as torrential rain caused water to spill over the Kaupakalua Dam. Elsewhere in the area, roads were flooded and bridges were washed out.

A surge of moisture that had pushed its way northward across part of the island chain over the weekend began to intensify at the start of the week, dumping inches of rainfall — and in some places more than a foot — over the islands.

In Haiku, an area on the island of Maui, 13.2 inches of rain fell between 7 a.m. and 3 p.m. on Monday, according to the National Weather Service, sparking the threat of flash flooding.

The rising floodwaters spurred state officials to order the evacuation of residents living downstream of the dam. They reported that heavy rains had led to the dam cresting. Paia Community Center, Hana High School and Eddie Tam Memorial Center were opened as evacuation shelters.

The Maui Fire Department reported receiving more than a dozen calls from residents trapped in their homes by rising flood waters on Monday as heavy rainfall overwhelmed the Hawaiian island of Maui, threatening to breach the Kaupakalua Dam.

Officials of the County of Maui issued a statement on Monday noting that while the Kaupakalua Dam was thought to have been breached by floodwaters, county officials later determined there was no structural damage after a closer inspection.

“(Water) has been coming over the top of the dam itself, but there has been no structural damage…” Maui County Mayor Michael Victorino said, according to Reuters. “So, the breaching that they thought was happening was because water was coming over. And some of them estimated that it had breached — but right now, to be perfectly honest, no breach.”

Shan Tsutsui, the chief operating officer of Mahi Pono, a co-owner of the dam, confirmed that water flowed over the top of the dam’s reservoir, but the dam itself did not fail, according to The Associated Press.

Crews in Maui will be checking on the integrity of the dam on Tuesday morning.

Flood evacuees, however, were still advised not to return to the area until officials deemed it safe to do so. The storm had not fully passed as of Tuesday morning.

“A storm will continue to bring heavy rains and locally strong east to southeast winds across the Hawaiian Islands through Tuesday,” AccuWeather Senior Meteorologist Paul Walker said. “Over the past 24 hours, Hilo, on the Big Island of Hawaii, received 5.41 inches.”

That’s nearly half the total amount of rainfall the town has received to date for the month. From the start of March to date, Hilo has recorded 12.07 inches of rainfall, about 90% of normal precipitation, 13.43, for the month. Still, the rainfall in Hilo didn’t even scratch the old daily rainfall record, which was set back in 2009 when 7.13 inches of rain fell.

In Ke’anae, on the island of Maui, more than 17 inches of rainfall fell over the past 36 hours as of 4 a.m. Tuesday, local time.

“Runoff from the heavy rains over the mountains has led to flash flooding in many places,” Walker said. “In Maui County, a section of the Hana Highway was closed because of the heavy rains.”

Maui County officials later announced the highway was reopened, though Kaupakalua Road was closed, and others nearby may be shut down as needed.

After surveying the flooding in Haiku on Monday, Victorino reported that Kaupakalua Road was impassible in some areas and about a half dozen homes were heavily damaged or destroyed. There was also evidence of landslides.

“Ladies and gentlemen, this is a real flooding situation we have not seen in a long time,” Victorino said in a live address on Facebook. “In fact, some of the residents have told me that this is the worst they’ve seen in over 25 years.”

He urged residents to stay off the roads and away from streams, rivers, culverts and drainage ditches, even if they are dry, and for people to stay away from the Haiku area for the safety of evacuees and emergency personnel.

“Visitors and residents should understand this is life-threatening flooding,” Victorino said.

Source: Adriana Navarro, AccuWeather