HONOLULU – Heavy rains are part of the winter wet season in Hawaiian Islands. But the downpours triggering flooding that destroyed homes and bridges and set off mass evacuations on multiple islands this week are also an example of the more intense rainstorms officials and climate scientists say are occurring more frequently as the planet warms.
Two key ingredients came together in Hawaii in recent days to deliver the rain: an upper-level disturbance and extra moisture in the lower layers of the atmosphere. The downpours first affected Maui, moved northward up the island chain to Oahu and Kauai, then circled around and hit the southernmost part of the Big Island.
Meteorologists on Wednesday extended a flash flood watch for the entire state through Friday because of the potential for more rain and because the ground was already saturated.
The onslaught destroyed and heavily damaged two Maui bridges, along with at least six homes on the island.
The rain filled a 138-year-old reservoir once used to irrigate sugar plantation fields. So much water accumulated it started overflowing from the 57-foot high structure at one point Monday, and county officials ordered people downstream to evacuate amid fears the earthen dam could breach. Ultimately, the reservoir didn’t fail, and water levels dropped as the rain let up.
The National Weather Service reported 13.2 inches fell over eight hours in the vicinity of the dam in Haiku on Maui’s north coast.
“This is really an example of climate change in the present day,” Suzanne Case, the head of the state agency that regulates the dam, the Department of Land and Natural Resources, said in a statement. “We have a flood emergency because of the heavy rain bomb. And we’re seeing these more and more across the island chain – more frequent and more extreme events.”
On Oahu, flooding covered roads and yards in towns on the eastern coast. Rising waters in the Opaelua Stream, which carries waters from the mountains down to the ocean, set off an evacuation order for the small town of Haleiwa, a mecca for big-wave surfers.
