Kona Low threatens Hawaii with torrential rain amid days of soaking

HONOLULU – Hawaii’s famous sunshine is taking a vacation of its own this week as a daylong pattern of thunderstorms sets in just offshore of the tropical islands, threatening heavy rain and flash flooding for the end of the week.

“The (forecast) model forecast for this week appears typical of mid-May in Hawaii, to say the least,” forecasters with the National Weather Service in Honolulu wrote in their Tuesday morning forecast discussion.

A Kona Low is expected to develop a few hundred miles north of the islands Tuesday evening and is expected to strengthen and meander just offshore for several days.

“Kona” comes from the Hawaiian word for “leeward” – the sheltered side of the trade winds typical of the Northeast. Kona’s lows are problematic because the winds reverse from the typical trade winds, bringing heavy rain to what are normally the leeward areas of the islands, sheltered from wind and rain.

WHAT IS A “WEAK KONA”?

Meanwhile, a large area of ​​deep tropical moisture lies just southwest of the islands, providing the nearby Kona Low with enough fuel to enhance precipitation.

This combination could lead to prolonged periods of heavy rain and thunderstorms until at least the end of the week.

Flood watches are in effect for all Hawaiian Islands from Wednesday morning through Friday evening. The heaviest rain is expected over Oahu and Maui Wednesday and Wednesday evening, slowly moving west to Kauai later Friday.

The NWS warned that significant flooding could occur due to overflowing streams and drainages, and that roads in several areas could be closed. Runoff can also cause property damage in urban areas.

“Landslides may also occur in areas with steep terrain,” the NWS said.

It’s already been a very humid week in Hawaii. Flood watches and warnings were posted on the islands over the weekend as a slow-moving storm system scraped the islands, with even winter storm conditions atop the Big Island’s mountain peaks.

POWERFUL STORM IN HAWAII BRINGS SEVERE WEATHER THREAT TO ISLANDS AND WINTER STORM WARNING FOR MOUNTAINS

Even Monday, before the Kona Low, flash flood warnings were in effect for east Oahu as a strong thunderstorm brought rainfall of 2 inches per hour, causing localized flooding.

Several rain gauges in Oahu’s higher elevations reported more than 8 inches of rain in the past 72 hours, with one rain gauge at St. Stephens Seminary near Kailua receiving more than 18 inches of rain in three days. A gauge in Kaneohe showed more than 9 inches in 72 hours, while the Marine Corps base in Kaneohe showed 5.01 inches for the same period.

While Wednesday’s flood warnings expire Friday evening, the NWS warned that the wet weather could persist into the weekend.