More than 2 trillion gallons of water—enough to fill 3 million Olympic-sized swimming pools—inundated �Ჹ�ɲ���ʻ�� in March. The accumulated rainfall over 14 days reached as high as 3,000% of normal historical levels for this time of year, culminating in a destructive “rain bomb” over ��ʻ�����. Through the University of �Ჹ�ɲ���ʻ��’s �Ჹ�ɲ���ʻ�� Mesonet and the �Ჹ�ɲ���ʻ�� Climate Data Portal, researchers captured the scale of these back-to-back Kona low systems, mapping localized threats and providing crucial data on the state’s severe flooding.

Between March 1 and March 23, statewide rainfall averaged 18.25 inches—more than 2.6 times the standard March average of 6.85 inches.

While the first storm (March 10–16) brought hurricane-force wind gusts of 135.4 mph to �Ჹ�ɲ���ʻ�� Island and up to 62 inches of rain to Maui, the second Kona storm between March 19 and 23 triggered a new wave of devastation. The second storm dumped up to 61 inches of rain in localized areas, producing destructive floods across eastern and central �ѴDZ��ǰ첹ʻ��, West Maui and ��ʻ�����.

Communities such as Waialua and Haleiwa on ��ʻ�����’s north shore experienced devastating inundation. �Ჹ�ɲ���ʻ�� Mesonet stations highlighted the widespread intensity of the storm: the ����ʻ������ station recorded the island’s highest two-day rainfall of roughly 22 inches, including 19.67 inches in a 24-hour period beginning the evening of March 19. Almost simultaneously, the nearby �����������ʻ�� Ridge station above Waimea Valley recorded 9.75 inches in 24 hours.

����ԴDz�, Palolo flash floods

As the two-week rainy period neared its end, an intense, localized atmospheric event struck ����ԴDz� and Palolo valleys on March 23. Honolulu Mayor Rick Blangiardi described it as a “classic rain bomb,” heavy rain caused by a stationary storm cell. This “rain bomb,” over ����ԴDz� and Palolo valleys, dropped 2 to 4 inches of rain per hour.

Six �Ჹ�ɲ���ʻ�� Mesonet stations in the Nuʻuanu-����ԴDz� area recorded between 3.5 and 6.5 inches of rain, the majority of which fell within a three-hour window. Falling on already saturated ground, this turned streams into raging torrents and triggered significant flash floods.

The �Ჹ�ɲ���ʻ�� Mesonet, a statewide network of state-of-the-art weather stations, is proving to be a critical source of weather information, especially valuable during extreme events.

“We are building the mesonet to serve multiple purposes, including research, resource management, support for farmers and ranchers, and others,” said Thomas Giambelluca, �Ჹ�ɲ���ʻ�� Mesonet project lead, and former director of the ����Vlog�ٷ� Water Resources Research Center. “But, providing data when and where it is most needed before and during extreme events like floods and wildfires, might be its most important purpose. Mesonet data will make us better prepared for future events by improving weather forecasts and enabling emergency managers to plan for and respond to extremes.”

For University of Hawaiʻi at Mānoa PhD student Brian Gorberg, the devastating Kona low storms weren’t just an academic research topic—they were a recurring nightmare that inundated his home three times in less than four weeks. Renting the bottom bedroom of a home in Waialua on Oʻahu’s north shore, Gorberg witnessed the final and most severe flood send an 8-foot wall of water through his place.

After experiencing two recent floods that ruined his belongings, Gorberg was seeking refuge at a friend’s house down the street when the third flood hit. The flash flooding was catastrophic, acting like a “dam spillway” through his neighborhood. The water destroyed his Jeep Patriot given to him by his dad, caused a neighboring house to spin off its foundation, and trapped another neighbor in neck-deep water.

“I got woken up by a giant wave,” Gorberg said. “I assumed the worst because I study hydrology. I assumed the dam failed and I knew I had to get out of the watershed. So, I drove all the way to the evacuation site. I actually ran up the hill because I didn’t believe the evacuation site was safe enough.”

Flooding expertise proved critical

Gorberg’s academic background proved critical during the floods. As an student in the and working with the under advisor Chris Shuler, his expertise allowed him to understand the mechanics of the disaster. During the floods, Gorberg spent hours walking through his neighborhood trying to warn residents ahead of the rising waters.

Gorberg’s current research work is to create high-end, reproducible flood models and stage height maps to better protect local communities. Working alongside undergraduate students Chiara Duyn, Megan Wong and Anne Dominique, Gorberg created a that provides residents with transparent, scenario-based flood information.

While the app and Gorberg’s maps currently focus on Windward ��ʻ����� watersheds such as Kāneʻohe, the underlying flood models are designed to be reproducible, and Gorberg aims to eventually expand this mapping to any flood zone across Hawaiʻi. The flood maps simulate exact inundation levels when local streams breach their banks at incremental heights—such as 12, 13 or 14 feet—allowing communities to visualize their risk and prepare for an approaching storm.

Reflecting on the tools he is building, Gorberg emphasized the urgent need for better preparedness in Hawaiʻi.

“Every stream gauge in the mainland has these maps. It’s not fair that Hawaiʻi doesn’t have it, especially considering these events,“ Gorberg said. ”And because there are graduate students like myself who have created this… that’s like the missing link in Hawaiʻi that would honestly solve this event, or would have been different if we had those maps.”

In the wake of historic flooding on Oʻahu’s North Shore, University of Hawaiʻi at ����ԴDz� (JABSOM) students continue to provide care where it’s urgently needed. On March 23, JABSOM’s Houseless Outreach and Medical Education (H.O.M.E.) Project—a student-run initiative that provides free healthcare to unsheltered and underserved communities—set up an on-site clinic at Waialua Elementary, treating 25 patients with a team of 16 student volunteers under the guidance of faculty.

“We’ve been seeing a wide range of patients. We’ve seen a fair amount with wounds and infections, probably from the storm water,” said Jill Omori, H.O.M.E. Project director.

Other patients sought care for back pain, joint pain and eye infections, conditions that can worsen when access to routine care is disrupted.

“We also saw people with GI (gastrointestinal) problems because of the contaminated water, but also just regular medical issues like hypertension or diabetes that still need to be controlled,” Omori said.

Student dedication and rural health disparities

The clinic weaves hands-on care into the JABSOM curriculum, but Omori said the majority of the students today came on their own time.

“A lot of times, the students come down to the North Shore and do service projects here and there,” Omori said. “But something like this really hits home for them. It’s really nice for them to be able to give back to the community this way.”

Second-year medical student Michael Ajimura saw that impact firsthand.

“A lot of people weren’t able to get care because of the past few days of flooding, as well as those who were injured helping out or because of the flooding,” Ajimura said. “Just being able to help them has been really rewarding. When we say that we care for the community, it’s everyone. Being out here is fulfilling, and it’s something a lot of the students are more than willing to do.”

The response also highlighted the broader issue of rural health in Hawaiʻi, which is exacerbated during a disaster.

“Rural health doesn’t just mean the neighbor islands,” Omori said. “Waialua is a great example of a rural community right here on Oʻahu. They have some of the same problems that other rural communities have, even without storms. I think it just emphasizes some of the rural health disparities and the need for more equitable care.”

As recovery continues on the North Shore, JABSOM’s H.O.M.E. Project plans to hold a pop-up clinic every day during the week of March 23. They will either be at Waialua District Park or at Haleiwa Beach Park. .

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