LIHUE — Another set of the year’s highest tides reached the archipelago Wednesday and Thursday, combined with swells from incoming Tropical Storm Erick and the beginning of a “black moon.”
Storm swells combined with King Tides Wednesday and Thursday. Tides reached 2.64 feet above normal in Hanalei Bay at 3:38 p.m. and are forecast to be at 2.53 feet at 4:18 p.m. today.
At Nawiliwili, tides reached 2.46 feet at 4:39 p.m. Thursday and today are predicted to reach 2.36 feet at 5:19 p.m. Tides at Port Allen reached 2.41 feet at 5:04 p.m. on Thursday and were predicted to reach 2.19 feet at 5:43 p.m. today. Waimea reached 2.03 feet at 5:26 p.m. on Thursday and tides are predicted to reach 1.88 feet on Friday at 6:06 p.m.
The scientific name for a King Tide is a perigean spring tide, and they coincide with full and new moons. Thursday was the first of two new moons in August — a rare occurrence known as a “black moon.”
According to University of Hawaii Sea Grant, King Tides show up when the moon is at its closest point to the Earth during its monthly orbit, and when the sun, moon and Earth are in alignment, combining their gravitational pulls.
Coastal geologists say they are not an unusual phenomenon, rather they are natural tides that got a flashy name.
“It’s just a larger tide that occasionally enhances the impact of the waves,” said coastal geologist Chuck Blay, who has been particularly studying Kauai’s Westside coasts. “It’s a natural occurrence. Someone just put the ‘King Tides’ (label) on it.”
While the tides are natural, they’re up against a backdrop of slow sea-level change, Blay pointed out, which can cause unusual flooding and other events.
“It’s not an unusual phenomenon, just an unusual combination of normal events,” he said.
That increase in sea-level rise has been documented by scientists, and that documentation has led to legislation and the creation of commissions on climate change in Hawaii.