The ferocity of the downpour that brought the latest Hawaii flooding surprised even meteorologists

“I was shocked to see how much flash flooding there was in my area,” said Manoa resident Andrew Phomsouvanh, who recorded video of streets transformed into a confluence of rapids. “The water just keeps coming.”

Natalie Aczon had gone to the drugstore to pick up some medication for her mother on Monday. By the time she left the store some 15 minutes later, water was roaring down the street next to the shopping center.

“People came running out from Longs and one of the guys actually said, ‘That’s my white car.’ And it had elevated,” she said.

The ferocity of Monday's downpour even took National Weather Service meteorologists aback. They knew that lingering instability from a powerful winter storm system called a “Kona low” could yield more rain, but their models aren't good at predicting how much moisture can remain in such systems, said forecaster Cole Evans.

“When you think it's over it's not quite over,” he said Tuesday.

The downpour, which dumped 2 to 4 inches (5 to 10 centimeters) of rain per hour, was highly localized: One rain gauge in the upper part of the valley recorded 6 inches (15 centimeters), while the airport a few miles away got just one-hundredth of an inch (less than a millimeter).

The Kona low was moving off to the east, Evans said, and should not pose further risk of bursts like Monday's. A flash flood was in effect for the eastern part of Maui.

There were no immediate reports of deaths or serious injuries, but authorities said hundreds of homes on Oahu's North Shore had been damaged by last week's flooding, which came as heavy rains fell on soil already saturated by downpours from a winter storm a week earlier.

More than 230 people had to be rescued. The water pushed houses off their foundations, floated cars out of parking spots and left walls, floor and counters covered with thick, reddish volcanic mud.

Evacuation orders covered 5,500 people north of Honolulu, and some residents fled on surfboards as water reached waist or chest high.

Farms around the state reported more than $9.4 million worth of damage as of Monday, according to a survey conducted by Agriculture Stewardship Hawaii, the Hawaii Farm Bureau and other organizations.

Even before Monday, Gov. Josh Green said the cost of the storm could top $1 billion, including damage to airports, schools, roads, homes and a Maui hospital in Kula. He called it the state’s most serious since flooding since 2004, when floods in Manoa inundated homes and a University of Hawaii library.

Green's office said Tuesday he had submitted a major disaster declaration request to the Trump administration.

Molly Pierce, a spokesperson for the Oahu Emergency Management Agency, said that in addition to volunteers and public workers who have been cleaning up, a contract company had arrived to begin collecting, sorting and removing large piles of debris.

She called the storm system “extremely unusual” but that officials were cautiously optimistic Tuesday that the rains are finally ending.

“Most of us have not seen something that just keeps going like this,” Pierce said. “We feel like we keep getting punched down. But we'll keep getting back up.”

The intensity and frequency of heavy rains in Hawaii have increased amid human-caused global warming, experts say.

Johnson reported from Seattle. Associated Press writer Mark Thiessen in Anchorage, Alaska, and Gabriela Aoun Angueira in San Diego contributed to this report.