National Weather Service issues flash flood watch as ‘deep moisture’ remains over state

All of Hawaii remains under a flash flood watch until at least this evening as heavy rains are predicted for the next several days.

Despite extreme weather on upcountry Maui, where heavy rain breached a Haiku dam and forced residents to evacuate Monday, the Big Island had comparably less rainfall during the past few days. However, the National Weather Service advises that conditions on all islands may be hazardous.


The NWS warns that significant flooding could occur, particularly in low-lying areas, as “deep moisture” remains over the state. Residents are advised to travel with caution and not attempt to cross any rising or moving water in a vehicle or on foot.

The NWS predicts a 100% chance of heavy rain in Hilo through today, and a 70% chance of showers every day this week.

The windward side of the Big Island has had a wet week already, with Hilo and Pahoa receiving nearly 5 inches of rain between Saturday and Monday. Papaikou received 7 inches of rain during the weekend, and Laupahoehoe received 9 inches.

Hilo, Hamakua and Puna districts were under a flood advisory through Monday evening, with the NWS estimating the heaviest showers falling at rates of 1-3 inches per hour.

By comparison, the leeward side of the island has been dry, with no site receiving much more than an inch of rain all weekend. However, all windward and leeward sites on the island remain under the flash flood watch.


None of the Big Island’s weekend rainfall has been particularly notable compared to other years, however. Hilo has received 6.5 inches of rain so far this month, less than half of the March rainfall received by this point in 2019.

The last precipitation record set on the Big Island was on Feb. 28, when 4.2 inches of rain fell on Hilo, exceeding the previous record, set in 1977, by about 0.4 inches.

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